Found 65 papers in cond-mat The urgent need for sustainable and innovative approaches to mitigate the
increasing levels of atmospheric CO$_2$ necessitates the development of
efficient methods for its removal. In this study, we focus on the synthesis and
functionalization of metal-organic framework (MOF) ZIF-8 at room temperature to
enhance its capacity for CO$_2$ capture. Specifically, we investigated the
impact of four amino-compounds, namely tetraethylenepentamine (TEPA),
hexadecylamine (HDA), ethanolamine (ELA), and cyclopropylamine (CPA), on the
chemical structure, size, surface area and porosity and CO$_2$ capturing of
ZIF-8 powder. By varying concentrations of the amino-compounds, we examined
their influence on the ZIF-8 properties. These results highlight the potential
of simple synthesis and functionalization techniques for MOFs in enhancing
their CO$_2$ capture capabilities. The findings from this study offer new
opportunities for the development of strategies to mitigate CO$_2$ emissions
using MOFs.
Exchange-coupled interfaces are pivotal in exploiting two-dimensional (2D)
ferromagnetism. Due to the extraordinary correlations among charge, spin,
orbital and lattice degrees of freedom, layered magnetic transition metal
chalcogenides (TMCs) bode well for exotic topological phenomena. Here we report
the realization of wafer-scale Cr2Te3 down to monolayer (ML) on insulating
SrTiO3(111) substrates using molecular beam epitaxy. Robust ferromagnetism
emerges in 2D Cr2Te3 ML with a Curie temperature TC = 17 K. Moreover, when
Cr2Te3 is proximitized with topological insulator (TI) (Bi,Sb)2Te3, the
magnetism becomes stronger -- for 1 ML, TC increases to 30 K, while for 2 ML it
boosts from 65 K to 82 K. Our experiments and theory strongly indicate that the
Bloembergen-Rowland interaction is likely a universal aspect of TC enhancement
in TI-coupled magnetic heterostructures. The topological-surface-enhanced
magnetism in 2D TMC enables further exchange coupling physics and quantum
hybrid studies, including paving the way to realize interface-modulated
topological electronics.
Eu$_5$In$_2$Sb$_6$ is a member of a family of orthorhombic nonsymmorphic
rare-earth intermetallics that combines large localized magnetic moments and
itinerant exchange with a low carrier density and perpendicular glide planes.
This may result in special topological crystalline (wallpaper fermion) or axion
insulating phases. Recent studies of Eu$_5$In$_2$Sb$_6$ single crystals have
revealed colossal negative magnetoresistance and multiple magnetic phase
transitions. Here, we clarify this ordering process using neutron scattering,
resonant elastic X-ray scattering, muon spin-rotation, and magnetometry. The
nonsymmorphic and multisite character of Eu$_5$In$_2$Sb$_6$ results in coplanar
noncollinear magnetic structure with an Ising-like net magnetization along the
$a$ axis. A reordering transition, attributable to competing ferro- and
antiferromagnetic couplings, manifests as the onset of a second commensurate
Fourier component. In the absence of spatially resolved probes, the
experimental evidence for this low-temperature state can be interpreted either
as an unusual double-$q$ structure or in a phase separation scenario. The net
magnetization produces variable anisotropic hysteretic effects which also
couple to charge transport. The implied potential for functional domain physics
and topological transport suggests that this structural family may be a
promising platform to implement concepts of topological antiferromagnetic
spintronics.
The plateau phase transition in quantum anomalous Hall (QAH) insulators
corresponds to a quantum state wherein a single magnetic domain gives way to
multiple magnetic domains and then re-converges back to a single magnetic
domain. The layer structure of the sample provides an external knob for
adjusting the Chern number C of the QAH insulators. Here, we employ molecular
beam epitaxy (MBE) to grow magnetic topological insulator (TI) multilayers with
an asymmetric layer structure and realize the magnetic field-driven plateau
phase transition between two QAH states with odd Chern number change {\Delta}C.
In multilayer structures with C=+-1 and C=+-2 QAH states, we find two
characteristic power-law behaviors between temperature and the scaling
variables on the magnetic field at transition points. The critical exponents
extracted for the plateau phase transitions with {\Delta}C=1 and {\Delta}C=3 in
QAH insulators are found to be nearly identical, specifically, k1~0.390+-0.021
and k2~0.388+-0.015, respectively. We construct a four-layer Chalker-Coddington
network model to understand the consistent critical exponents for the plateau
phase transitions with {\Delta}C=1 and {\Delta}C=3. This work will motivate
further investigations into the critical behaviors of plateau phase transitions
with different {\Delta}C in QAH insulators and provide new opportunities for
the development of QAH chiral edge current-based electronic and spintronic
devices.
We systematically construct two-dimensional $\mathbb{Z}_3$ symmetry-protected
topological (SPT) three-state Potts paramagnets with gapless edge modes on a
triangular lattice. First, we study microscopic lattice models for the gapless
edge and, using the density-matrix renormalization group (DMRG) approach,
investigate the finite size scaling of the low-lying excitation spectrum and
the entanglement entropy. Based on the obtained results, we identify the
universality class of the critical edge, namely the corresponding conformal
field theory and the central charge. Finally, we discuss the inherent
symmetries of the edge models and the emergent winding symmetry distinguishing
between two SPT phases. As a result, the two topologically nontrivial and the
trivial phases define a general one-dimensional chain supporting a
tricriticality, which we argue supports a gapless SPT order in one dimension.
We demonstrate that a class of stable $\mathbb{Z}_2$ monopole charge Dirac
point ($\mathbb{Z}_2$DP) phases can robustly exist in real materials, which
surmounts the understanding: that is, a $\mathbb{Z}_2$DP is unstable and
generally considered to be only the critical point of a $\mathbb{Z}_2$ nodal
line ($\mathbb{Z}_2$NL) characterized by a $\mathbb{Z}_2$ monopole charge (the
second Stiefel-Whitney number $w_2$) with space-time inversion symmetry but no
spin-orbital coupling. For the first time, we explicitly reveal the
higher-order bulk-boundary correspondence in the stable $\mathbb{Z}_2$DP phase.
We propose the alternating-twisted multilayer graphene, which can be regarded
as 3D twisted bilayer graphene (TBG), as the first example to realize such
stable $\mathbb{Z}_2$DP phase and show that the Dirac points in the 3D TBG are
essential degenerate at high symmetric points protected by crystal symmetries
and carry a nontrivial $\mathbb{Z}_2$ monopole charge ($w_2=1$), which results
in higher-order hinge states along the entire Brillouin zone of the $k_z$
direction. By breaking some crystal symmetries or tailoring interlayer coupling
we are able to access $\mathbb{Z}_2$NL phases or other $\mathbb{Z}_2$DP phases
with hinge states of adjustable length. In addition, we present other 3D
materials which host $\mathbb{Z}_2$DPs in the electronic band structures and
phonon spectra. We construct a minimal eight-band tight-binding lattice model
that captures these nontrivial topological characters and furthermore tabulate
all possible space groups to allow the existence of the stable $\mathbb{Z}_2$DP
phases, which will provide direct and strong guidance for the realization of
the $\mathbb{Z}_2$ monopole semimetal phases in electronic materials,
metamaterials and electrical circuits, etc.
\textit{Holey Graphene} (HG) is a widely used graphene material for the
synthesis of high-purity and highly crystalline materials. In this work, we
explore the electronic properties of a periodic distribution of lattice holes,
demonstrating the emergence of flat bands with compact localized states. It is
shown that the holes break the bipartite sublattice and inversion symmetries,
inducing gaps and a nonzero Berry curvature. Moreover, the folding of the Dirac
cones from the hexagonal Brillouin zone (BZ) to the holey superlattice
rectangular BZ of HG with sizes proportional to an integer $n$ times the
graphene's lattice parameter leads to a periodicity in the gap formation such
that $n \equiv 0$ (mod $3$). Meanwhile, it is shown that if $n \equiv \pm 1$
(mod $3$), a gap emerges where Dirac points are folded along the $\Gamma-X$
path. The low-energy hamiltonian for the three central bands is also obtained,
revealing that the system behaves as an effective $\alpha-\mathcal{T}_{3}$
graphene material. Therefore, a simple protocol is presented here that allows
obtaining flat bands at will. Such bands are known to increase
electron-electron correlated effects. This work provides an alternative system,
much easier to build than twisted systems, to obtain highly correlated quantum
phases.
Using Hubbard U corrected density functional theory calculations, lattice
Monte-Carlo, and spin-Monte-Carlo simulations, we investigate the impact of
dopant clustering on the magnetic properties of WSe2~doped with period four
transition metals. We use manganese (Mn) and iron (Fe) as candidate n-type
dopants and vanadium (V) as the candidate p-type dopants, substituting the
tungsten (W) atom in WSe2. Specifically, we determine the strength of the
exchange interaction in the Fe-, Mn-, and V-doped WSe2~ in the presence of
clustering. We show that the clusters of dopants are energetically more stable
than discretely doped systems. Further, we show that in the presence of dopant
clustering, the magnetic exchange interaction significantly reduces because the
magnetic order in clustered WSe2~becomes more itinerant. Finally, we show that
the clustering of the dopant atoms has a detrimental effect on the magnetic
interaction, and to obtain an optimal Curie temperature, it is important to
control the distribution of the dopant atoms.
One of the most remarkable theoretical findings in magic angle twisted
bilayer graphene (TBG) is the emergence of ferromagnetic Slater determinants as
exact ground states for the interacting Hamiltonian at the chiral limit. This
discovery provides an explanation for the correlated insulating phase which has
been experimentally observed at half filling. This work is the first
mathematical study of interacting models in magic angle graphene systems. These
include not only TBG but also TBG-like systems featuring four flat bands per
valley, and twisted trilayer graphene (TTG) systems with equal twist angles. We
identify symmetries of the Bistritzer-MacDonald Hamiltonian that are
responsible for characterizing the Hartree-Fock ground states as zero energy
many-body ground states. Furthermore, for a general class of Hamiltonian, we
establish criteria that the ferromagnetic Slater determinants are the unique
ground states within the class of uniformly half-filled, translation invariant
Slater determinants. We then demonstrate that these criteria can be explicitly
verified for TBG and TBG-like systems at the chiral limit, using properties of
Jacobi-$\theta$ and Weierstrass-$\wp$ functions.
In the present work, thermal transport and energy conversation in two
thermoelectrically efficient candidates of Janus SnSSe and SnS$_2$ are
investigated within the non-equilibrium Monte Carlo simulation of phonon
Boltzmann equation. The phonon analysis is performed to determine the
contributed phonons in heat transport. The results present that the dominant
participating phonons are longitudinal acoustic ones while the least belongs to
the transverse acoustic (TA) mode. Both materials reached the very high maximum
temperature in response to the implied wasted heat. This is attributed to the
low presence of the critical TA phonons. Also, the temperature profile achieved
during the heating and cooling of the materials is studied. It is obtained that
the heat propagation through the SnS$_2$ is, at first, swifter, which results
in a temperature gradient through the whole material which is less than that of
the SnSSe. As the time passes, the heat transfer that is directly related to
the material thermal conductivity, slows down. So, the behavior of the SnS$_2$
and SnSSe, in case of the heat propagation status, becomes similar. More, the
behavior of the thermoelectric figure of merit (zT), the efficiency ($\eta$),
and the generated voltage have been figured out. It is stated that the higher
zT and $\eta$ do not guarantee a larger generated Seebeck voltage. This is
true, while the generated Seebeck voltage is related to the temperature
difference between the heated and the cold junction. Accordingly, how far the
temperature of matter rises in response to the implied wasted heat is related
to the obtained voltage. Mainly, it is presented that the maximum temperature
that a material achieves, alongside the temperature gradient and material
property Seebeck coefficient, are essential in introducing thermoelectrically
efficient materials with reasonable thermal to electrical energy conversion.
MoTe2 is a paradigmatic van der Waals layered semimetal with two
energetically close electronic phases, the topologically trivial 1Tprime and
the low-temperature Td type-II Weyl semimetal phase. The ability to manipulate
this phase transition, perhaps towards occurring near room temperature, would
open new avenues for harnessing the full potential of Weyl semimetals for
high-efficiency electronic and spintronic applications. Here, we show that
potassium dosing on 1Tprime-MoTe2 induces a Lifshitz transition by a
combination of angle-resolved photoemission spectroscopy, scanning tunneling
microscopy, x-ray spectroscopy and density functional theory. While the
electronic structure shifts rigidly for small concentrations of K, MoTe2
undergoes significant band structure renormalization for larger concentrations.
Our results demonstrate that the origin of this electronic structure change
stems from alkali metal intercalation. We show that these profound changes are
caused by effectively decoupling the 2D sheets, bringing K-intercalated
1Tprime-MoTe2 to the quasi-2D limit, but do not cause a topological phase
transition.
PtTe$_2$ and PdTe$_2$ are among the first transition metal dichalcogenides
that were predicted to host type-II Dirac fermions, exotic particles prohibited
in free space. These materials are layered and air-stable, which makes them top
candidates for technological applications that take advantage of their
anisotropic magnetotransport properties. Here, we provide a detailed
characterization of the electronic structure of PtTe$_2$ and PdTe$_2$ using
Angle Resolved Photoemission Spectroscopy ARPES and Density Functional Theory
DFT calculations, unveiling a new three-dimensional Dirac-like dispersion in
these materials. Through the use of circularly polarized light, we report a
different behavior of such dispersion in PdTe$_2$ compared to PtTe$_2$, that we
relate to our DFT calculations. Additionally, our circular dichroism data shows
a sharp difference between the known type-II Dirac cones and the topologically
protected surface states in these materials. Finally, we present an analysis
that links our experimental and theoretical data to the different symmetries
associated to the crystallographic space group shared by PtTe$_2$ and PdTe$_2$.
Our work provides a useful reference for the ARPES characterization of other
transition metal dichalcogenides with topological properties and illustrates
the use of circular dichroism as an additional tool to differentiate the
topological character of two otherwise equivalent band dispersions and to
identify new dispersions.
We show that the particular loop-current order for twisted bi-layer graphene
(TBG) at the carbon length-scale together with modulations on the moir\'e
length scale proposed by Blutinck et al. maps to the xy model. Some
experimental evidence in unstrained TBG at various fillings is consistent with
this order at both scales while strained samples appear to show such an order
at the carbon length scale but a kekule order at the moir\'e length scale. We
pay special attention to deriving the coupling of fermions to the fluctuations
of the xy model. The previous solution of the quantum xy model coupled to the
fermions serves three purposes. (1) derivation of the $\omega/T$ scaling of the
propagator of the fluctuations whose coupling to fermions gives the observed
linear in temperature resistivity and other marginal Fermi-liquid properties
which could tested in future experiments. (2) It provides the topological
defects to which an externally applied magnetic field couples to give a
resistivity proportional to $H_z$, and (3) it provides the mechanism for
instability of the quantum fluctuating state to superconductivity in d-wave
symmetry. Further experiments are required to ascertain the assumed symmetries
of the order.
The rapid development of artificial intelligence (AI) is driving significant
changes in the field of atomic modeling, simulation, and design. AI-based
potential energy models have been successfully used to perform large-scale and
long-time simulations with the accuracy of ab initio electronic structure
methods. However, the model generation process still hinders applications at
scale. We envision that the next stage would be a model-centric ecosystem, in
which a large atomic model (LAM), pre-trained with as many atomic datasets as
possible and can be efficiently fine-tuned and distilled to downstream tasks,
would serve the new infrastructure of the field of molecular modeling. We
propose DPA-2, a novel architecture for a LAM, and develop a comprehensive
pipeline for model fine-tuning, distillation, and application, associated with
automatic workflows. We show that DPA-2 can accurately represent a diverse
range of chemical systems and materials, enabling high-quality simulations and
predictions with significantly reduced efforts compared to traditional methods.
Our approach paves the way for a universal large atomic model that can be
widely applied in molecular and material simulation research, opening new
opportunities for scientific discoveries and industrial applications.
Hypothesis: Droplet coalescence process is important in many applications and
has been studied extensively when two droplets are surrounded by gas. However,
the coalescence dynamics would be different when the two droplets are
surrounded by an external viscous liquid. The coalescence of immiscible
droplets in liquids has not been explored. Experiments: In the present
research, the coalescence of two immiscible droplets in low- and high-viscosity
liquids is investigated and compared with their miscible counterparts
experimentally. The coalescence dynamics is investigated via high-speed
imaging, and theoretical models are proposed to analyze the growth of the
liquid bridge. Findings: We find that, the liquid bridge $r$ evolves
differently due to the constraint from the triple line in the bridge region,
which follows $r\propto {{t}^{{2}/{3}}}$ for low-viscosity surroundings. While
for high-viscosity surroundings, the liquid bridge grows at a constant velocity
${{u}_{r}}$ which varies with the surrounding viscosity ${{\mu }_{s}}$ as
${{u}_{r}}\propto {{\mu }_{s}}^{{1}/{2}}$. In the later stage of the bridge
growth, the bridge evolution again merges with the well-established power-law
regime $r\propto {{t}^{{1}/{2}}}$, being either in low or high-viscosity
liquids. Moreover, a new inertia-viscous-capillary timescale is proposed, which
unifies the combined influence of inertia, viscous, and capillary forces on the
evolution of the liquid bridge in liquid environments, highlighting the joint
role of inertia and viscous resistance in the coalescence process.
Crystalline topological insulators have recently become a powerful platform
for realizing photonic topological states from microwaves to the visible.
Appropriate geometric symmetries of the lattice are at the core of their
functionality. Here we put forward an alternative approach to craft those
systems by designing the internal symmetries of the Hamiltonian via accidental
mode degeneracies. We illustrate our approach constructing ananalog of
breathing honeycomb lattice using simpler lattice geometry and six times less
meta-atoms, reveal edge and corner states and calculate the relevant
topological invariants.
The formalism of the Rokhsar-Kivelson (RK) model has been frequently used to
study topological phase transitions in 2D in terms of the deformed
wavefunctions, which are RK-type wavefunctions. A key drawback of the deformed
wavefunctions is that the obtained quantum critical points are RK-type, in the
sense that the equal-time correlation functions are described by 2D conformal
field theories (CFTs). The generic Lorentz invariant quantum critical points
described by (2+1)D CFTs can not be obtained from the deformed wavefunctions.
To address this issue, we generalize the deformed wavefunction approach to the
deformed thermofield double (TFD) state methodology. Through this extension, we
can effectively reconstruct the absent temporal dimension at the RK-type
quantum critical point. We construct deformed TFD states for a (1+1)D quantum
phase transition from a symmetry-protected topological phase to a
symmetry-breaking phase, and for generic (2+1)D topological phase transitions
from a $\mathbb{Z}_2$ topologically ordered phase to a trivial paramagnetic
phase.
We present a framework to take new measurements in nematic systems that
contain active elements such as molecular motors. Spatio-temporal fields of
stress, velocity, pressure, and forces are obtained jointly from microscopy
images. Our inverse-problem approach ensures that they comply with physical
laws and are accurate near system boundaries. Our measurements in active
biological materials provide new insight for the design of boundary-aware
nematic systems. The shear stress unveils a correlation with the nucleation of
topological defects. The velocity and pressure fields characterize how boundary
effects drive the dynamics of the system in terms of attractors. And the force
relates the underlying fluid with the nematic tensor to reveal the activity
scales of the system. More broadly, our work establishes a generalizable
approach to study experimental systems that are inaccessible to measuring
probes.
In a molecule formed by two atoms, energy difference between bonding and
antibonding orbitals should depend on distance of the two atoms. However,
exploring molecular orbitals of two natural atoms with tunable distance has
remained an outstanding experimental challenge. Graphene quantum dots (GQDs)
can be viewed as relativistic artificial atoms, therefore, offering a unique
platform to study molecular physics. Here, through scanning tunneling
microscope (STM), we create and directly visualize the formation process of
relativistic artificial molecules based on two coupled GQDs with tunable
distance. Our study indicates that energy difference between the bonding and
antibonding orbitals of the lowest quasibound state increases linearly with
inverse distance of the two GQDs due to the relativistic nature of the
artificial molecule. For quasibound states with higher orbital momenta, the
coupling between these states leads to half-energy spacing of the confined
states because the length of the molecular-like orbit is about twice that of
the atomic-like orbit. Evolution from ring-like whispering-gallery modes in the
artificial atoms to figure-eight orbitals in the artificial molecules is
directly imaged. The ability to resolve the coupling and orbitals of the
relativistic artificial molecule at the nanoscale level yields insights into
the behavior of quantum-relativistic matter.
Magnetic skyrmions with topologically nontrivial spin textures form a variety
of periodic structures depending on microscopic interactions and lattice
symmetry. We theoretically investigate a transformation between triangular and
square skyrmion crystals against an external magnetic field in a polar
tetragonal magnet. By performing the simulated annealing for a classical spin
model, we show that the competition of the Dzyaloshinskii-Moriya interaction at
multiple wave vectors is a key ingredient in inducing the structural transition
in terms of the skyrmion crystals. The present results indicate the importance
of magnetic frustration in momentum space as the origin of exotic topological
phase transitions.
We study the planar Hall effect (PHE), and reexamine the Lifshitz invariants
in the spin-orbit coupled superconductors. In the Rashba superconductor, the
PHE is finite as fluctuations are faster along the applied field than
perpendicular to it. We consider spin-orbit splitting that is larger than the
critical temperature. In this regime the Cooper pairs are predominantly
intra-band. The effective two-band interaction matrix elements are not
sensitive enough to the field to affect the PHE. However, in a wide range of
parameters this dependence does modify the Lifshitz invariant, linear in field
and responsible for the spin diode effect. This contribution is a geometrical
effect of the adjustment of the spin texture to the applied field. As such, it
also allows the repulsion or attraction in the spin triplet channel to affect
the Lifshitz invariant. While the PHE can be studied within the effective
two-band superconductor model with an original pairing interaction, the
Lifshitz invariant, in general, cannot. Disorder is shown to only moderately
suppress the PHE.
We present a scheme to generate shell-shaped droplet in a three-component
(1,2,3) ultracold Bose gas. Here binary mixtures (1,2) and (2,3) form quantum
droplets due to inter-species attractions, and the two droplets are mutually
immiscible due to strong 1-3 repulsion. Importantly, the shared component-2
serves as a glue to link the two droplets together as a globally self-bound
object. In this system, the outer droplet naturally develops a shell structure,
and its radius and width can be conveniently tuned through the size of core
droplet. Moreover, to reach an equilibrium with the shell, the core droplet
displays very different spin densities as compared to the vacuum case. These
results have been demonstrated in a realistic $^{23}$Na-$^{39}$K-$^{41}$K
mixture. Our scheme liberates the shell-shaped Bose gas from stringent
conditions with microgravity or fine-tuned traps, and can be readily
implemented in cold atoms laboratories on Earth. This paves the way for future
exploration of quantum droplets in curved space with non-trivial real-space
topologies.
Topology and correlations are fundamental concepts in modern physics, but
their simultaneous occurrence within a single quantum phase is exceptionally
rare. In this study, we present the discovery of such a phase of matter in
Ta2Pd3Te5, a semimetal where the Coulomb interaction between electrons and
holes leads to the spontaneous formation of excitonic bound states below T=100
K. Our spectroscopy unveils the development of an insulating gap stemming from
the condensation of these excitons, thus giving rise to a highly sought-after
correlated quantum phase known as the excitonic insulator. Remarkably, our
scanning tunneling microscopy measurements reveal the presence of gapless
boundary modes in the excitonic insulator state. Their magnetic field response
and our theoretical calculations suggest a topological origin of these modes,
rendering Ta2Pd3Te5 as the first experimentally identified topological
excitonic insulator in a three-dimensional material not masked by any
structural phase transition. Furthermore, our study uncovers a secondary
excitonic instability below T=5 K, which differs from the primary one in having
finite momentum. We observe unprecedented tunability of its wavevector by an
external magnetic field. These findings unlock a frontier in the study of novel
correlated topological phases of matter and their tunability.
We investigate the collisions of Majorana zero modes, which are presented as
inter-soliton collisional events in fermionic superfluids with spin-orbit
coupling. Our results demonstrate that, the zero energy splitting, induced by
the overlapping of inter-soliton Majorana wave-functions upon collision,
generates an effective repulsive force for Majorana states, which in turn
protected themselves against into bulk excitation. As a result, the collision
between solitons associated with Majorana zero modes appears to be repulsive
and elastic, as they do not penetrate each other but instead repel without
energy loss. As well, similar repulsive behavior is observed in collisions
between soliton-induced and defect-pinned Majorana zero modes. Our research
offers new insights into the features of Majorana fermions, and robustness in
the collisions of Majorana zero modes bodes well for the prospects of
topological quantum computation with a multitude of Majorana qubits.
The optical absorption spectrum of $C_{60}$-dimers and polymers was
investigated by Kikuo et al. in 1996\cite{harigaya1996charge}. As a compliment
to these earlier studies, the optical absorption spectrum of the $C_{70}$
fullerene has been investigated in the present study. The main purpose was then
to compare the absorption spectrum of the $C_{70}$-dimers and trimers and, more
specifically, to clarify the effect of these molecular structures on the
absorption spectrum. What is most important and decisive is then the value of
the conjugation parameter of these $C_{70}$-based molecules. In the present
study, a tight-binding model was used in calculating the optical absorption
spectra of both $C_{70}$ dimers and polymers, as well as $C_{70}$ trimers and
polymers. The change in conjugation parameter for each of these species was
found to cause variations in the corresponding optical absorption spectrum. It
was found that the absorption tensor of the $C_{70}$ trimer and the polymer
was, depending on the value of the conjugation parameters $b=0.5$ and $b=0.8$.
The situation was almost the same for the conjugation parameters $b=0.1$ and
$b=0.2$. In addition, the value of the band gap was also different depending on
the different conjugation parameters, with a reduced value for the larger
values of this parameter. As a conclusion, smaller values of the conjugation
parameter were not found to have a large effect on the absorption spectrum of
the $C_{70}$-dimers and trimers, or in other words, the effect was hardly
visible. On the contrary, the larger values caused a drastic change in the
optical absorption spectrum of the $C_{70}$-dimers and trimers.
As a key ingredient in energy harvesting and photodetection,
light-to-electricity conversion requires efficient separation of photoexcited
electron-hole pairs before recombination. Traditional junction-based mechanisms
mainly use build-in electric fields to achieve pair separation and generate
photovoltaic effect, which fail to collect photoexcited pairs away from local
barrier region. The ability to harvest photovoltaic effect in a homogeneous
material upon uniform illumination is appealing, but has only been realized in
very few cases such as non-centrosymmetric systems through bulk photovoltaic
effect. Here we realize a new type of photovoltaic effect, termed as
acousto-drag photovoltaic effect, by travelling surface acoustic waves (t-SAW)
in a conventional layered semiconductor MoSe2. Instead of immediately driving
the electron-hole pairs to opposite directions after generation, t-SAW induces
periodic modulation to electronic bands and drags the photoexcited pairs toward
the same travelling direction. The photocurrent can then be extracted by a
local barrier, e.g. the metal-semiconductor contact as we used here. By
spatially separating the electron-hole generation and extraction processes, the
acousto-drag mechanism strongly suppresses charge recombination and yields
large nonlocal photoresponse outside the barrier region. We show that when
t-SAW is applied, the photoresponse can be enhanced by over two orders of
magnitude with exceptionally high external quantum efficiency above 60%. The
discovery of acousto-drag photovoltaic effect establishes a new approach
towards efficient light-to-electricity conversion without the restriction of
crystal symmetry.
Magnon polarons are novel elementary excitations possessing hybrid magnonic
and phononic signatures, and are responsible for many exotic spintronic and
magnonic phenomena. Despite long-term sustained experimental efforts in chasing
for magnon polarons, direct spectroscopic evidence of their existence is hardly
observed. Here, we report the direct observation of magnon polarons using
neutron spectroscopy on a multiferroic Fe$_{2}$Mo$_{3}$O$_{8}$ possessing
strong magnon-phonon coupling. Specifically, below the magnetic ordering
temperature, a gap opens at the nominal intersection of the original magnon and
phonon bands, leading to two separated magnon-polaron bands. Each of the bands
undergoes mixing, interconverting and reversing between its magnonic and
phononic components. We attribute the formation of magnon polarons to the
strong magnon-phonon coupling induced by Dzyaloshinskii-Moriya interaction.
Intriguingly, we find that the band-inverted magnon polarons are topologically
nontrivial. These results uncover exotic elementary excitations arising from
the magnon-phonon coupling, and offer a new route to topological states by
considering hybridizations between different types of fundamental excitations.
We give the most general formulation for gauging of generalized symmetry, in
terms of the language of higher linear algebra. In short, generalized gauging
is just condensation of designated topological operators. Our framework covers
all known variants of gauging, and may be used to discover unknown ones. In
particular, we proved that gauging is always reversible: the original theory
and the gauged theory are Morita equivalent; similarly, the original symmetry
and the gauge symmetry are also Morita equivalent.
Recent advances in the study of materials with topological electronic band
structures have revealed magnetic materials exhibiting giant anomalous Hall
effects (AHE). The giant AHE has not only attracted the research interest in
its mechanism but also opened up the possibility of practical application in
magnetic sensors. In this article, we describe simulation-based investigations
of AHE magnetic sensors for the applications to read head sensors (readers) of
hard disk drives. With the shrinking of magnetic recording patterns, the reader
technology, which currently uses multilayer-based tunnel magnetoresistance
(TMR) devices, is associated with fundamental challenges, such as insufficient
spatial resolution and signal-to-noise ratio (SNR) in sensors with dimensions
below 20 nm. The structure of an AHE-based device composed of a single
ferromagnetic material is advantageous for magnetic sensors with nanoscale
dimensions. We found that AHE readers using topological ferromagnets with giant
AHE, such as Co2MnGa, can achieve a higher SNR than current TMR readers. The
higher SNR originates from the large output signal of the giant AHE as well as
from the reduced thermal magnetic noise, which is the dominant noise in TMR
readers. We highlight a major challenge in the development of AHE readers: the
reduction in the output signal due to the shunting of the bias current and the
leakage of the Hall voltage through the soft magnetic shields surrounding the
AHE reader. We propose reader structures that overcome this challenge. Finally,
we discuss the scope for future research to realize AHE readers.
Floquet topological insulators have been widely investigated in
lower-dimensional systems. However, Floquet topological insulators in
higher-dimensional systems remain unexplored. In this work, we study the
effects of time-periodic driving in a four-dimensional (4D) normal insulator,
focusing on topological phase transitions at the resonant quasienergy gap. We
consider two types of time-periodic driving, including a time-periodic onsite
potential and a time-periodic vector potential. We reveal that both types of
the time-periodic driving can transform the 4D normal insulator into a 4D
Floquet topological insulator characterized by an emergent second Chern number.
Moreover, it is found that the topological phase of the 4D system can be
modulated by tuning the strength of the time-periodic driving. Our work will be
helpful for future investigations on Floquet topological insulators in higher
dimensions.
Transition-metal dichalcogenides (TMDs) host tightly bound quasi-particles
called excitons. Based on spin and momentum selection rules, these excitons can
be either optically bright or dark. In tungsten-based TMDs, momentum-forbidden
dark exciton is the energy ground state and therefore it strongly affect the
emission properties. In this work, we brighten the momentum forbidden dark
exciton by placing WS$_2$ on top of nanotextured substrates which put the
WS$_2$ layer under tensile strain, modifying electronic bandstructure. This
enables phonon assisted scattering of exciton between momentum valleys, thereby
brightening momentum forbidden dark excitons. Our results will pave the way to
design ultrasensitive strain sensing devices based on TMDs.
In the magic angle twisted bilayer graphene (MATBG), non-Fermi liquid like
transport phenomena are universally observed. To understand their origin, we
perform the self-consistent analysis of the self-energy due to SU(4) valley +
spin fluctuations induced by the electron-electron correlation. In the SU(4)
fluctuation mechanism, the fifteen channels of fluctuations contribute
additively to the self-energy. Therefore, the SU(4) fluctuation mechanism gives
much higher electrical resistance than the spin fluctuation mechanism. By the
same reason, SU(4) fluctuations of intermediate strength provide $T$-linear
resistivity down to $\sim1$K. Interestingly, the $T$-linear resistivity is
robustly realizedfor wide range of electron filling, even away from the
van-Hove filling. This study provides a strong evidence for the importance of
electron-electron correlation in MATBG.
Mn$_3$Sn has garnered significant attention due to its kagome lattice,
120$^\circ$ noncollinear antiferromagnetic order, and substantial anomalous
Hall effect. In this study, we comprehensively explore intrinsic and extrinsic
contributions to anomalous Hall, anomalous Nernst, and anomalous thermal Hall
effects, employing first-principle calculations and group theory analysis.
Comparative analysis between our theoretical results and available experimental
data underscores the predominance of intrinsic mechanism in shaping anomalous
transport properties at low temperatures. Specifically, Weyl fermions are
identified as the primary contributors to intrinsic anomalous Hall
conductivity. The significance of extrinsic mechanisms becomes evident at high
temperatures, especially when the longitudinal charge conductivity falls into
the dirty regime, where the side jump mechanism plays a vital role. Extrinsic
contributions to anomalous transport properties are primarily influenced by the
electronic states residing at the Fermi surfaces. Furthermore, anomalous
transport properties exhibit periodic variations when subjected to spin
rotations within the kagome plane, achievable by applying an external magnetic
field. Our findings advance the understanding of anomalous transport phenomena
in Mn$_3$Sn and offer insights into potential applications of noncollinear
antiferromagnetic materials in spintronics and spin caloritronics.
We report a comprehensive first-principles study of the relative stability of
the various possible crystal structures, and the electronic and optical
properties of ternary alkali metal chalcogenides ACuX (A= Na/K and X= S/Se/Te)
compounds through density functional theory (DFT) calculations. The energetics
and phonon spectra of greater than 700 structures were compared, and seven
possible stabilized structures of six ACuX compounds were identified using the
fixed composition evolutionary search method. Our electronic band structure
simulation confirms that all the ternary ACuX compounds are direct band gap
semiconductors, with the band gap lying between 0.83 eV to 2.88 eV. These
compounds exhibit directly allowed electronic transitions from the valence band
to the conduction band, which leads to a significant strength of optical
transition probability. This yields a sharp rise in the optical absorption
spectra (ranging between 10$^4$ to 10$^5$ cm$^{-1}$) near the energy gap. The
estimated spectroscopic limited maximum efficiency (SLME) is about 18% for an 8
$\mu$m thick NaCuTe film. For other ACuX compounds, the SLME ranges between 10%
to 13%. In addition, we also explored the feasibility of these ternary ACuX
compounds for photocatalytic water splitting applications and found that they
can be promising candidates as photocathodes for hydrogen evolution reactions.
With a large spread in the band gap and interesting band topology near Fermi
level, these chalcogenides can be quite fertile for other energy applications
such as thermoelectric, LED, etc.
The subtle interplay between competing degrees of freedom, anisotropy, and
spin correlations in frustrated Kitaev quantum materials offer an ideal
platform to host myriads of non-trivial quantum states with exotic fractional
excitations. The signature of spin-freezing behavior of these spin-orbit driven
frustrated magnets is characterized by a bifurcation of zero-field-cooled and
field-cooled magnetic susceptibility at low temperatures much below the
characteristic interaction energy scale. The magnetic-specific heat exhibits a
T^2 dependence below the freezing temperature. The field-independent behavior
of magnetic-specific heat below the freezing temperature implies the presence
of exotic low-energy excitations. The aging and memory effect experiments in
the Kitaev magnets suggest the non-hierarchical free energy distribution, which
differs from the hierarchical organization of conventional spin-freezing.
Furthermore, NMR spin-lattice relaxation rate follows a power law behavior
below the spin-freezing temperature suggesting the persistence of
unconventional spin excitation spectra. Herein, we demonstrate that the
observed low-temperature spin-freezing phenomena in a few representative Kitaev
quantum materials can be effectively explained by the Halperin and Saslow (HS)
hydrodynamic modes relevant for non-trivial spin glass materials. The linearly
dispersive HS modes are hypothesized to account for instigating non-abelian
defect propagation, thereby inducing a spin jam state in the low-temperature
regime in frustrated Kitaev magnets. Our investigation reveals that HS modes
capture the essence of unconventional spin-freezing ascribed to topological
origin in two-dimensional (2D) Kitaev magnets decorated on a honeycomb lattice
and its 3D analog hyperhoneycomb that offers a viable ground to extend this
framework to a large class of frustrated quantum materials.
We have calculated the dynamical polarization, plasmons and damping rates in
semi-Dirac bands (SDB's) with zero band gap and half-linear, half-parabolic
low-energy spectrum. The obtained plasmon dispersions are strongly anisotropic
and demonstrate some crucial features of both two-dimensional electron gas and
graphene. Such gapless energy dispersions lead to a localized area of undamped
and low-damped plasmons in a limited range of the frequencies and wave vectors.
The calculated plasmon branches demonstrate an increase of their energies for a
finite tilting of the band structure and a fixed Fermi level which could be
used as a signature of a specific tilted spectrum in a semi-Dirac band.
We study the emergence of interfacial modes between the two regions of a
semi-Dirac type material, which are illuminated by the left and right
circularly polarized light, respectively. We show that a smooth boundary
between the two regions give rise to an interfacial quantum well which is
sensitive to the incoming electron's momentum. The quantum well is found to
host the Volkov-Pankratov states which are gapless metallic in nature. Contrary
to the inverted mass term, it is the inverted velocity term that induces such
states across the boundary. We also note that incident electron can fully pass
over the interfacial well without any reflection only at certain light
parameters-known as {\it Ramsauer-Townsend} effect. Moreover, we also observe
that such modes can even exist across the interface between the irradiated and
non-irradiated regions under certain condition.
We consider magnetic Weyl metals as a platform to achieve current control of
magnetization textures with transport currents, utilizing their underlying band
geometry. We show that the transport current in a Weyl semimetal produces an
axial magnetization due to orbital magnetic moments of the Weyl electrons. The
associated axial magnetization can generate a torque acting on the localized
magnetic moments. For the case of a magnetic vortex in a nanodisk of Weyl
materials, this current-induced torque can be used to reverse its circulation
and polarity. We discuss the axial magnetization torques in Weyl metals on
general symmetry grounds, and compare their strength to current-induced torques
in more conventional materials.
The 5/2 fractional quantum Hall effect in the second Landau level of
extremely clean two-dimensional electron gases has attracted much attention due
to its topological order predicted to host quasiparticles that obey non-Abelian
quantum statistics and could serve as a basis for fault-tolerant quantum
computations. While previous works have establish the Fermi liquid (FL) nature
of its putative composite fermion (CF) normal phase, little is known regarding
its thermodynamics properties and as a result its effective mass is entirely
unknown. Here, we report on time-resolved specific heat measurements at filling
factor 5/2, and we examine the ratio of specific heat to temperature as a
function of temperature. Combining these specific heat data with existing
longitudinal thermopower data measuring the entropy in the clean limit we find
that, unless a phase transition/crossover gives rise to large specific heat
anomaly, both datasets point towards a large effective mass in the FL phase of
CFs at 5/2. We estimate the effective-to-bare mass ratio m*/me to be ranging
from ~2 to 4, which is two to three times larger than previously measured
values in the first Landau level.
We consider a superconductor-barrier-superconductor (S-B-S) sandwich
configuration built with Rarita-Schwinger-Weyl semimetal featuring four band
crossings at a single nodal point. Assuming a homogenous s-wave pairing in each
superconducting region, and the barrier region created by applying a voltage of
magnitude $V_0 $ across a piece of normal state semimetal, we apply the BdG
formalism to compute the discreet energy spectrum $\varepsilon $ of the subgap
Andreev bound states in the short-barrier regime. In contrast with the two-band
semimetals studied earlier, we find upto four pairs of localized states (rather
than one pair for two-band semimetals) in the thin-barrier limit, and each
value of $\varepsilon $ has a complicated dependence on the phase difference
$\varphi_{12} $ via cosine and sine functions, which cannot be determined
analytically. These are artifacts of multiple band crossings hosting
quasiparticles of pseudospin value greater than $1/2$. Using the bound state
energies, we compute the Josephson current across the junction configuration.
Twisted bilayer graphene (TBG) can host the moir\'{e} energy flat bands with
two-fold degeneracy serving as a fruitful playground for strong correlations
and topological phases. However, the number of degeneracy is not limited to
two. Introducing a spatially alternative magnetic field, we report that the
induced magnetic phase becomes an additional controllable parameter and leads
to an undiscovered generation of four-fold degenerate flat bands. This
emergence stems from the band inversion at $\Gamma$ point near the Fermi level
with a variation of both twisted angle and magnetic phase. We present the
conditions for the emergence of multi-fold degenerate flat bands, which are
associated with the eigenvalue degeneracy of a Birman-Schwinger operator. Using
holomorphic functions, which explain the origin of the double flat bands in the
conventional TBG, we can generate analytical wave functions in the magnetic TBG
to show absolute flatness with four-fold degeneracy. Moreover, we identify an
orbital-related intervalley coherent state as the many-body ground state at
charge neutrality. In contrast, the conventional TBG has only two moir\'{e}
energy flat bands, and the highly degenerate flat bands with additional orbital
channels in this magnetic platform might bring richer correlation physics.
Van der Waals heterostructures have recently emerged as an exciting platform
for investigating the effects of strong electronic correlations, including
various forms of magnetic or electrical orders. Here, we perform an unbiased
exact diagonalization study of the effects of interactions on topological flat
bands of twisted transition metal dichalcogenides (TMDs) at odd integer
fillings. For hole-filling $\nu_h = 1$, we find that Chern insulator phases,
expected from interaction-induced spin-valley polarization of the bare bands,
are quite fragile, and give way to spontaneous multiferroic order -- coexisting
ferroelectricity and ferromagnetism, in presence of long-range Coulomb
repulsion. We provide a simple real-space picture to understand the phase
diagram as a function of interaction range and strength. Our findings establish
twisted TMDs as a novel and highly tunable platform for multiferroicity, with
potential applications to electrical control of magnetism.
Amorphous alumina is employed ubiquitously as a high-dielectric-constant
material in electronics, and its thermal-transport properties are of key
relevance for heat management in electronic chips and devices. Experiments show
that the thermal conductivity of alumina depends significantly on the synthesis
process, indicating the need for a theoretical study to elucidate the atomistic
origin of these variations. Here we employ first-principles simulations to
characterize the atomistic structure, vibrational properties, and thermal
conductivity of alumina at densities ranging from 2.28 g/cm3 to 3.49 g/cm3.
Moreover, using an interatomic potential trained on first-principles data, we
investigate how system size affects predictions of the thermal conductivity,
showing that simulations containing 120 atoms can already reproduce the bulk
limit of the conductivity. Finally, relying on the recently developed Wigner
formulation of thermal transport, we shed light on the interplay between
atomistic topological disorder and anharmonicity in the context of heat
conduction, showing that the former dominates over the latter in determining
the conductivity of alumina.
Recent studies have found that fluctuations of magnetization transfer in
integrable spin chains violate the central limit property. Here we revisit the
problem of anomalous counting statistics in the Landau-Lifshitz field theory by
specializing to two distinct anomalous regimes featuring a dynamical critical
point. By performing optimized numerical simulations using an integrable
space-time discretization we extract the algebraic growth exponents of
time-dependent cumulants which attain their threshold values. The distinctly
non-Gaussian statistics of magnetization transfer in the easy-axis regime is
found to converge towards the universal distribution of charged single-file
systems. At the isotropic point we infer a weakly non-Gaussian distribution,
corroborating the view that superdiffusive spin transport in integrable spin
chains does not belong to any known dynamical universality class.
We study the effect of the energy gap on the transmission of fermions in
graphene exposed to linearly polarized light as a laser barrier. We determine
the energy spectrum, apply boundary conditions at interfaces, and use the
transfer matrix approach to obtain transmissions for all energy modes. We show
that when the energy gap increases, the oscillations of transmissions decrease
dramatically until they vanish entirely. However, when the barrier width
varies, the oscillations become more significant and exhibit sharp peaks. By
increasing the incident energy, the laser field suppresses the Fabry-P\'erot
resonance, and the transmissions move to the right when the energy gap is
tuned.
Understanding the role of lattice geometry in shaping topological states and
their properties is of fundamental importance to condensed matter and device
physics. Here we demonstrate how an anisotropic crystal lattice drives a
topological hybrid nodal line in transition metal tetraphosphides $Tm$P$_4$
($Tm$ = Transition metal). $Tm$P$_4$ constitutes a unique class of black
phosphorus materials formed by intercalating transition metal ions between the
phosphorus layers without destroying the characteristic anisotropic band
structure of the black phosphorous. Based on the first-principles calculations
and $k \cdot p$ theory, we show that $Tm$P$_4$ harbor a single hybrid nodal
line formed between oppositely-oriented anisotropic $Tm~d$ and P states
unhinged from the high-symmetry planes. The nodal line consists of both type-I
and type-II nodal band crossings whose nature and location are determined by
the effective-mass anisotropies of the intersecting bands. We further discuss a
possible topological phase transition to exemplify the formation of the hybrid
nodal line state in $Tm$P$_4$. Our results offer a comprehensive study for
understanding the interplay between structural motifs-driven mass anisotropies
and topology in anisotropic lattice materials to realize hybrid semimetal
states.
The Hamiltonian of a two dimensional (2D) magnetic material in the strong
correlation regime with a spin texture, for which both azimuthal and polar
angle changes, is solved using $su(2)$ path integral method. The dependence of
the Chern number on the atomic spin ($S$), azimuthal angle ($\vec{q}_{1}$) and
polar angle ($\vec{q}_{2}$) modulation vector of the spin texture on a
bipartite honeycomb lattice is found. For $S \leq 3$ it was found that Chern
number depends strongly on $\vec{q}_{2}$ and $S$. We discuss applicability of
the model to several van der Waals magnets. Experimentally, it is expected
that, with increase in spin modulation vector the sign of the topological Hall
conductivity changes, $+\sigma_{xy}^{THE} \to -\sigma_{xy}^{THE}$ or
vice-versa, when $S$ is constant. We also propose several heterostrucures for
experimental realization of this effect.
We investigate the electronic properties of a hybrid system that comprises
single-bilayer graphene structures subjected to a perpendicular magnetic field.
Specifically, our focus is on the behavior exhibited by the zigzag boundaries
of the junction, namely Zigzag-1 (ZZ1) and Zigzag-2 (ZZ2), using the continuum
Dirac model for rigorous analysis. Our findings reveal a striking dependence of
conductance on the width of the bilayer graphene at ZZ1, providing essential
insights into the transport behavior of this boundary. Moreover, we observe a
captivating phenomenon where the conductance at ZZ2 exhibits prominent maxima,
demonstrating a robust correlation with the applied magnetic field.
Additionally, our investigation uncovers the profound impact of interfaces on
transmission probability, with ZZ1 being notably more affected compared to ZZ2.
The variation of the Fermi energy further highlights the significant influence
of magnetic field strength on the system's conductive properties, resulting in
distinct conductance characteristics between the two regions. The combined
results of ZZ1 and ZZ2 provide valuable insights into the system's transport
properties. Notably, a clear exponential-like trend in conductance variation
with the applied magnetic field underscores the system's strong sensitivity to
magnetic changes.
We theoretically calculate the dynamic structure factor of two-dimensional
Rashba-type spinorbit coupled (SOC) Fermi superfluid with random phase
approximation, and analyse the main characters of dynamical excitation sh own
by both density and spin dynamic structure factor during a continuous phase
transition between Bardeen-Cooper-Schrieffer superfluid and topological
superfluid. Generally we find three different excitations, including collective
phonon excitation, two-atom molecular and atomic excitations, and pair-breaking
excitations due to two-branch structure of quasi-particle spectrum. It should
be emphasized that collective phonon excitation is overlapped with a gapless DD
type pair-breaking excitation at the critical Zeeman field hc, and is imparted
a finite width to phonon peak when transferred momentum q is around Fermi
vector kF. At a much larger transferred momentum (q = 4kF ), the pair-breaking
excitation happens earlier than two-atom molecular excitation, which is
different from the conventional Fermi superfluid without SOC effect.
We study the transport properties of Dirac fermions through gapped graphene
through a magnetic barrier irradiated by a laser field oscillating in time. We
use Floquet theory and the solution of Weber's differential equation to
determine the energy spectrum corresponding to the three regions composing the
system. The boundary conditions and the transfer matrix approach {are} employed
to explicitly determine the transmission probabilities for multi-energy bands
and the associated conductance. As an illustration, we focus only on the three
first bands: the central band $T_0$ (zero photon exchange) and the two first
side bands $T_{\pm1}$ (photon emission or absorption). It is found that the
laser field activates the process of translation through photon exchange.
Furthermore, we show that varying the incident angle and energy gap strongly
affects the transmission process. The conductance increases when the number of
electrons that cross the barrier increases, namely when there is a significant
transmission.
We directly measured the interactions between a hydrophobic solid and a
hydrophobic liquid separated by water using force spectroscopy, where colloidal
probes were coated with graphene oxide (GO) to interact with immobilized
heptane droplets in water. We detected attractions with a long range of ~0.5
microns, which cannot be readily explained by standard
Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. When the GO was reduced to
become more hydrophobic, these forces increased in strength and ranged up to
1.2 microns, suggesting that the hydrophobic nature of the involved surfaces
critically influences the observed long-range forces. Previous studies have
addressed such hydrophobic attractions, but were limited to solid/water/solid
and solid/water/air scenarios. Here we expand this knowledge to include the
solid/water/liquid situation. Based on our results, we propose air bubbles
attached to the colloidal probe and molecular rearrangement at the water/oil
interface as possible origins of the observed interactions. The proposed
mechanism expands insights gained from previous to the solid/water/liquid
situation and is universally applicable to describe attractive interactions
between hydrophobic bodies of any kind separated by water. Our work will be
useful to understand and motivate the formation of many colloid and interface
phenomena, including emulsions using 2D materials and other
amphiphilic/hydrophobic particles.
In our previous work, we synthesized a metal/2D material heterointerface
consisting of $L1_0$-ordered iron-palladium (FePd) and graphene (Gr) called
FePd(001)/Gr. This system has been explored by both experimental measurements
and theoretical calculations. In this study, we focus on a heterojunction
composed of FePd and multilayer graphene referred to as
FePd(001)/$m$-Gr/FePd(001), where $m$ represents the number of graphene layers.
We perform first-principles calculations to predict their spin-dependent
transport properties. The quantitative calculations of spin-resolved
conductance and magnetoresistance (MR) ratio (150-200%) suggest that the
proposed structure can function as a magnetic tunnel junction in spintronics
applications. We also find that an increase in $m$ not only reduces conductance
but also changes transport properties from the tunneling behavior to the
graphite $\pi$-band-like behavior. Additionally, we investigate the
spin-transfer torque-induced magnetization switching behavior of our
\color{blue} junction structures \color{black} using micromagnetic simulations.
Furthermore, we examine the impact of lateral displacements (``sliding'') at
the interface and find that the spin transport properties remain robust despite
these changes; this is the advantage of two-dimensional material
hetero-interfaces over traditional insulating barrier layers such as MgO.
We study an analytically solvable and experimentally relevant
number-conserving periodically driven $p$-wave superconductor. Such a system is
found to support generalized Majorana zero and $\pi$ modes which, despite being
non-Hermitian, are still capable of encoding qubits. Moreover, appropriate
winding numbers characterizing the topology of such generalized Majorana modes
are defined and explicitly calculated. We further discuss the fate of the
obtained generalized Majorana modes in the presence of finite charging energy.
Finally, we shed light on the quantum computing prospects of such modes by
demonstrating the robustness of their encoded qubits and explicitly braiding a
pair of generalized Majorana modes.
We study the chiral symmetry breaking and metastability of confined nematic
lyotropic chromonic liquid crystal (LCLC) with and without chiral dopants. The
isotropic-nematic coexistence phase of the LCLC renders two confining
geometries: sessile isotropic(I) droplets surrounded by the nematic(N) phase
and sessile nematic droplets immersed in the isotropic background. In the
achiral system with no dopants, LCLC's elastic anisotropy and topological
defects induce a spontaneous twist deformation to lower the energetic penalty
of splay deformation, resulting in spiral optical textures under crossed
polarizers both in the I-in-N and N-in-I systems. While the achiral system
exhibits both handednesses with an equal probability, a small amount of the
chiral dopant breaks the balance. Notably, in contrast to the homochiral
configuration of a chirally doped LCLC in bulk, the spiral texture of the
disfavored handedness appears with a finite probability both in the I-in-N and
N-in-I systems. We propose director field models explaining how chiral symmetry
breaking arises by the energetics and the opposite-twist configurations exist
as meta-stable structures in the energy landscape. These findings help us
create and control chiral structures using confined LCs with large elastic
anisotropy.
We systematically and analytically construct a set of spinor wave functions
representing defects and textures that continuously penetrate interfaces
between coexisting, topologically distinct magnetic phases in a spin-2
Bose-Einstein condensate. These include singular and nonsingular vortices
carrying mass or spin circulation that connect across interfaces between
biaxial- and uniaxial nematic, cyclic and ferromagnetic phases, as well as
vortices terminating as monopoles on the interface ("boojums"). The
biaxial-nematic and cyclic phases exhibit discrete polytope symmetries
featuring non-Abelian vortices and we investigate a pair of non-commuting line
defects within the context of a topological interface. By numerical
simulations, we characterize the emergence of non-trivial defect core
structures, including the formation of composite defects. Our results
demonstrate the potential of spin-2 Bose-Einstein condensates as experimentally
accessible platforms for exploring interface physics, offering a wealth of
combinations of continuous and discrete symmetries.
We determine the phase diagrams of anisotropic Kitaev-Heisenberg models on
the honeycomb lattice using parton mean-field theories based on different
Majorana fermion representations of the $S=1/2$ spin operators. Firstly, we use
a two-dimensional Jordan-Wigner transformation (JWT) involving a semi-infinite
snake string operator. In order to ensure that the fermionized Hamiltonian
remains local we consider the limit of extreme Ising exchange anisotropy in the
Heisenberg sector. Secondly, we use the conventional Kitaev representation in
terms of four Majorana fermions subject to local constraints, which we enforce
through Lagrange multipliers. For both representations we self-consistently
decouple the interaction terms in the bond and magnetization channels and
determine the phase diagrams as a function of the anisotropy of the Kitaev
couplings and the relative strength of the Ising exchange. While both
mean-field theories produce identical phase boundaries for the topological
phase transition between the gapless and gapped Kitaev quantum spin liquids,
the JWT fails to correctly describe the the magnetic instability and
finite-temperature behavior. Our results show that the magnetic phase
transition is first order at low temperatures but becomes continuous above a
certain temperature. At this energy scale we also observe a finite temperature
crossover on the quantum spin-liquid side, from a fractionalized paramagnet at
low temperatures, in which gapped flux excitations are frozen out, to a
conventional paramagnet at high temperatures.
The discovery of graphene led to a burst in search for 2D materials
originating from layered atomic crystals coupled by van der Waals force. While
bulk bismuth crystals share this layered crystal structure, unlike other group
V members of the periodic table, its interlayer bonds are stronger such that
traditional mechanical cleavage and exfoliation techniques have shown to be
inefficient. In this work, we present a novel mechanical cleavage method for
exfoliating bismuth by utilizing the stress concentration effect induced by
micro-trench SiO2 structures. As a result, the exfoliated bismuth flakes can
achieve thicknesses down to the sub-10 nm range which are analyzed by AFM and
Raman spectroscopy.
The vast high entropy alloy (HEA) composition space is promising for
discovery of new material phases with unique properties. We explore the
potential to achieve rare-earth-free high magnetic anisotropy materials in
single-phase HEA thin films. Thin films of FeCoNiMnCu sputtered on thermally
oxidized Si/SiO$_{2}$ substrates at room temperature are magnetically soft,
with a coercivity on the order of 10 Oe. After post-deposition rapid thermal
annealing (RTA), the films exhibit a single face-centered-cubic (fcc) phase,
with an almost 40-fold increase in coercivity. Inclusion of 50 at.% Pt in the
film leads to ordering of a single L1$_{0}$ high entropy intermetallic phase
after RTA, along with high magnetic anisotropy and a 3 orders of magnitude
coercivity increase. These results demonstrate a promising HEA approach to
achieve high magnetic anisotropy materials using RTA.
Quasi-one-dimensional (Q1D) Cr-based pnictide K$_2$Cr$_3$As$_3$ has aroused
great research interest due to its possible triplet superconducting pairing
symmetry. Recent experiments have shown that incorporating hydrogen atoms into
K$_2$Cr$_3$As$_3$ would significantly change its electronic and magnetic
properties. Hence, it's necessary to investigate the impact of hydrogen doping
in superconducting pairing symmetry of this material. Employing the hydrogen as
an non-trivial electron-doping, our calculates show that, different from the
$p_z$-wave obtained without hydrogen, the system exhibits $p_x\pm ip_y$ pairing
superconductivity under specific hydrogen doping. Specifically, we adopt the
random-phase-approximation approach based on a six-band tight-binding model
equipped with multi-orbital Hubbard interactions to study the hydrogen-doping
dependence of the pairing symmetry and superconducting $T_c$. Under the
rigid-band approximation, our pairing phase diagram shows the spin-triplet
pairing states is dominated through out the hydrogen-doping regime $x\in
(0,0.7)$. Particularly, the $T_c\sim x$ curve shows a peak at the 3D-quasi-1D
Lifshitz transition point, and the pairing symmetry around this doping level is
$p_x\pm ip_y$. The physical origin of this pairing symmetry is that the density
of states is mainly concentrated at $k_x(k_y)$ with large momentum. Due to the
three-dimensional character of the real material, this $p_x\pm ip_y$-wave
superconducting state possesses point gap nodes. We further provide experiment
prediction to identify this triplet $p_x\pm ip_y$-wave superconductivity.
Gauging is a powerful operation on symmetries in quantum field theory (QFT),
as it connects distinct theories and also reveals hidden structures in a given
theory. We initiate a systematic investigation of gauging discrete generalized
symmetries in two-dimensional QFT. Such symmetries are described by topological
defect lines (TDLs) which obey fusion rules that are non-invertible in general.
Despite this seemingly exotic feature, all well-known properties in gauging
invertible symmetries carry over to this general setting, which greatly
enhances both the scope and the power of gauging. This is established by
formulating generalized gauging in terms of topological interfaces between
QFTs, which explains the physical picture for the mathematical concept of
algebra objects and associated module categories over fusion categories that
encapsulate the algebraic properties of generalized symmetries and their
gaugings. This perspective also provides simple physical derivations of
well-known mathematical theorems in category theory from basic axiomatic
properties of QFT in the presence of such interfaces. We discuss a
bootstrap-type analysis to classify such topological interfaces and thus the
possible generalized gaugings and demonstrate the procedure in concrete
examples of fusion categories. Moreover we present a number of examples to
illustrate generalized gauging and its properties in concrete conformal field
theories (CFTs). In particular, we identify the generalized orbifold groupoid
that captures the structure of fusion between topological interfaces
(equivalently sequential gaugings) as well as a plethora of new self-dualities
in CFTs under generalized gaugings.
We discuss the two-step transitions in superconductors, where the
intermediate state between the Cooper pair state and the normal metal is the
4-fermion condensate, which is called the intertwined vestigial order. We
discuss different types of the vestigial order, which are possible in the
spin-triplet superfluid $^3$He, and the topological objects in the vestigial
phases. Since in $^3$He the order parameter $A_{\alpha i}$ represents the
analog of gravitational tetrads, we suggest that the vestigial states are
possible in quantum gravity. As in superconductors, the fermionic vacuum can
experience two consequent phase transitions. At first transition the metric
appears as the bilinear combination of tetrads $g_{\mu\nu} =\eta_{ab}< \hat
E^a_\mu \hat E^b_\nu>$, while the tetrad order parameter is still absent,
$e_\mu^a=< \hat E^a_\mu> =0$. This corresponds to the bosonic Einstein general
relativity, which emerges in the fermionic vacuum. The nonzero tetrads
$e_\mu^a=< \hat E^a_\mu> \neq 0$ appear at the second transition, where a kind
of the Einstein-Cartan-Sciama-Kibble tetrad gravity is formed. This suggests
that on the levels of particles, gravity acts with different strength on
fermions and bosons.
Odd-parity superconductivity is a rare and sought-for state of matter with a
potential for applications in topological quantum computing. Crystals with
staggered locally non-centrosymmetric structures have been proposed as
platforms where a magnetic field can induce a transition between even- and
odd-parity superconducting (SC) states. The superconductor CeRh$_2$As$_2$ with
a critical temperature $T_{\mathrm{c}}\approx0.4\,\mathrm{K}$ is likely the
first example material showing such a phase transition at a magnetic field
$\mu_{0}H^{*}=4\,\mathrm{T}$ applied along the crystallographic $c$ axis.
CeRh$_2$As$_2$ also undergoes a phase transition of an unknown origin at
$T_{0}=0.5\,\mathrm{K}$ and presents signs of an antiferromagnetism below
$0.25\,\mathrm{K}$. Under a hydrostatic pressure of
$P_0\approx0.5\,\mathrm{GPa}$, the $T_{0}$ order vanishes, resulting in a
quantum critical point. Here, using resistivity measurements under pressure, we
investigate how the correlations and normal-state orders affect the SC phase
switching. We find an enhancement of the in-plane critical field near $P_0$. At
the same time, the two SC states persist well past $P_{0}$, until at least
$2.7\,\mathrm{GPa}$ and $H^{*}$ is reduced to $0.3\,\mathrm{T}$, making the
putative odd-parity state stable almost down to zero field.
Swarmalators are oscillators that swarm through space as they synchronize in
time. Introduced a few years ago to model many systems which mix synchrony with
self-assembly, they remain poorly understood theoretically. Here we obtain the
first analytic results on swarmalators moving in two-dimensional (2D) plane by
enforcing periodic boundary conditions; this simpler topology allows
expressions for order parameters, stabilities, and bifurcations to be derived
exactly. We suggest some future directions for swarmalator research and point
out some connections to the Kuramoto model and the Vicsek model from active
matter; these are intended as a call-to-arms for the sync community and other
researchers looking for new problems and puzzles to work on.
In this paper, we introduce an algorithm for extracting topological data from
translation invariant generalized Pauli stabilizer codes in two-dimensional
systems, focusing on the analysis of anyon excitations and string operators.
The algorithm applies to $\mathbb{Z}_d$ qudits, including instances where $d$
is a nonprime number. This capability allows the identification of topological
orders that may differ from $\mathbb{Z}_d$ toric codes, thereby extending the
scope beyond the established theorem that Pauli stabilizer codes of
$\mathbb{Z}_p$ qudits (with $p$ being a prime) are equivalent to finite copies
of $\mathbb{Z}_p$ toric codes and trivial stabilizers. The algorithm is
designed to determine all anyons and their string operators, enabling the
computation of their fusion rules, topological spins, and braiding statistics.
The method converts the identification of topological orders into computational
tasks, including Gaussian elimination, the Hermite normal form, and the Smith
normal form of truncated Laurent polynomials. Furthermore, the algorithm
provides a systematic approach for studying quantum error-correcting codes. We
apply it to various codes, such as self-dual CSS quantum codes modified from
the color code and non-CSS quantum codes that contain the double semion
topological order or the six-semion topological order.
Family Puzzle or Generation Problem demands an explanation of why there are 3
families or generations of quarks and leptons in the Standard Model of particle
physics. Here we propose a novel solution -- the multiple of 3 families of 16
Weyl fermions (namely $(N_f=3) \times 16$) in the 3+1d spacetime dimensions are
topologically robust due to constraints rooted in profound mathematics (such as
Hirzebruch signature and Rokhlin theorems, and cobordism) and derivable in
physics (such as chiral edge states, quantized thermal Hall conductance, and
gravitational Chern-Simons theory), which holds true even forgetting or getting
rid of any global symmetry or gauge structure of the Standard Model. By the
dimensional reduction through a sequence of sign-reversing mass domain wall of
domain wall and so on, we reduce the Standard Model fermions to obtain the
$(N_f=3) \times 16$ multiple of 1+1d Majorana-Weyl fermion with a total chiral
central charge $c_-=24$. Effectively via the fermionization-bosonization, the
1+1d theory becomes 3 copies of $c_-=8$ of (E$_8)_1$ conformal field theory,
living on the boundary of 3 copies of 2+1d E$_8$ quantum Hall states. Based on
the framing anomaly-free $c_- = 0 \mod 24$ modular invariance, the framed
bordism and string bordism $\mathbb{Z}_{24}$ class, the 2-framing and
$p_1$-structure, the $w_1$-$p_1$ bordism $\mathbb{Z}_3$ class constraints, we
derive the family number constraint $N_f \in (\frac{48}{16} =\frac{24}{8}=3)
\mathbb{Z}$. The dimensional reduction process, although not necessary, is
sufficiently supported by the $\mathbb{Z}_{16}$ class Smith homomorphism. We
also comment on the $\frac{45}{15}=3$ relation: the 3 families of 15
Weyl-fermion Standard Model vacuum where the absence of some sterile
right-handed neutrinos is fulfilled by additional topological field theories or
conformal field theories in Ultra Unification.

Date of feed: Wed, 27 Dec 2023 01:30:00 GMT**Search terms: **(topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)|(flatband)|(flat.{1}band)|(LK.{1}99) **Amine-Modified ZIF-8 for Enhanced CO$_2$ Capture: Synthesis, Characterization and Performance Evaluation. (arXiv:2312.14974v1 [cond-mat.mtrl-sci])**

Viktorie Neubertova, Vaclav Svorcik, Zdenka Kolska

**Enhanced Ferromagnetism in Monolayer Cr2Te3 via Topological Insulator Coupling. (arXiv:2312.15028v1 [cond-mat.mtrl-sci])**

Yunbo Ou, Murod Mirzhalilov, Norbert M. Nemes, Jose L. Martinez, Mirko Rocci, Austin Akey, Wenbo Ge, Dhavala Suri, Yiping Wang, Haile Ambaye, Jong Keum, Mohit Randeria, Nandini Trivedi, Kenneth S. Burch, David C. Bell, Weida Wu, Don Heiman, Valeria Lauter, Jagadeesh S. Moodera, Hang Chi

**Unusual magnetism of the axion-insulator candidate Eu$_5$In$_2$Sb$_6$. (arXiv:2312.15054v1 [cond-mat.str-el])**

M. C. Rahn, M. N. Wilson, T. J. Hicken, F. L. Pratt, C. Wang, F. Orlandi, D. D. Khalyavin, P. Manuel, L. S. I. Veiga, A. Bombardi, S. Francoual, P. Bereciartua, A. S. Sukhanov, J. D. Thompson, S. M. Thomas, P. F. S. Rosa, T. Lancaster, F. Ronning, M. Janoschek

**Engineering Plateau Phase Transition in Quantum Anomalous Hall Multilayers. (arXiv:2312.15072v1 [cond-mat.mes-hall])**

Deyi Zhuo, Ling-Jie Zhou, Yi-Fan Zhao, Ruoxi Zhang, Zi-Jie Yan, Annie G. Wang, Moses H. W. Chan, Chao-Xing Liu, Chui-Zhen Chen, Cui-Zu Chang

**Two-dimensional topological paramagnets protected by $\mathbb{Z}_3$ symmetry: Properties of the boundary Hamiltonian. (arXiv:2312.15095v1 [cond-mat.str-el])**

Hrant Topchyan, Vasilii Iugov, Mkhitar Mirumyan, Tigran S. Hakobyan, Tigran A. Sedrakyan, Ara G. Sedrakyan

**Stable Higher-Order Topological Dirac Semimetals with $\mathbb{Z}_2$ Monopole Charge in Alternating-twisted Multilayer Graphenes and beyond. (arXiv:2312.15131v1 [cond-mat.mes-hall])**

Shifeng Qian, Yongpan Li, Cheng-Cheng Liu

**Flat bands without twists: periodic holey graphene. (arXiv:2312.15165v1 [cond-mat.mes-hall])**

Abdiel de Jesús Espinosa-Champo, Gerardo G. Naumis

**Reduction of Magnetic Interaction Due to Clustering in Doped Transition-Metal Dichalcogenides: A Case Study of Mn, V, Fe-Doped $\rm WSe_2$. (arXiv:2312.15171v1 [cond-mat.mtrl-sci])**

Sabyasachi Tiwari, Maarten Van de Put, Bart Soree, Christopher Hinkle, William G. Vandenberghe

**Exact ground state of interacting electrons in magic angle graphene. (arXiv:2312.15314v1 [math-ph])**

Simon Becker, Lin Lin, Kevin D. Stubbs

**Energy conversion in thermoelectric materials of SnSSe and SnS$_2$: a Monte-Carlo simulation of Boltzmann transport equation. (arXiv:2312.15331v1 [cond-mat.mes-hall])**

Seyedeh Ameneh Bahadori, Zahra Shomali

**Lifshitz Transition and Band Structure Renormalization in Alkali Metal Intercalated 1Tprime-MoTe2. (arXiv:2312.15360v1 [cond-mat.mtrl-sci])**

Joohyung Park, Ayan N. Batyrkhanov, Jonas Brandhoff, Marco Gruenewald, Felix Otto, Maximilian Schaal, Saban Hus, Torsten Fritz, Florian Göltl, An-Ping Li, Oliver L.A. Monti

**Observation of a new three-dimensional Dirac-like dispersion in the type-II Dirac semimetals PtTe2 and PdTe2. (arXiv:2312.15371v1 [cond-mat.mes-hall])**

Ivan Pelayo, Derek Bergner, Archibald J. Williams, Jiayuwen Qi, Mahfuzun Nabi, Warren L. B. Huey, Luca Moreschini, Ziling Deng, Jonathan Denlinger, Alessandra Lanzara, Wolfgang Windl, Joshua Goldberger, Claudia Ojeda-Aristizabal

**Quantum-criticality in twisted bi-layer graphene. (arXiv:2312.15410v1 [cond-mat.str-el])**

C. M. Varma

**DPA-2: Towards a universal large atomic model for molecular and material simulation. (arXiv:2312.15492v1 [physics.chem-ph])**

Duo Zhang, Xinzijian Liu, Xiangyu Zhang, Chengqian Zhang, Chun Cai, Hangrui Bi, Yiming Du, Xuejian Qin, Jiameng Huang, Bowen Li, Yifan Shan, Jinzhe Zeng, Yuzhi Zhang, Siyuan Liu, Yifan Li, Junhan Chang, Xinyan Wang, Shuo Zhou, Jianchuan Liu, Xiaoshan Luo, Zhenyu Wang, Wanrun Jiang, Jing Wu, Yudi Yang, Jiyuan Yang, Manyi Yang, Fu-Qiang Gong, Linshuang Zhang, Mengchao Shi, Fu-Zhi Dai, Darrin M. York, Shi Liu, Tong Zhu, Zhicheng Zhong, Jian Lv, Jun Cheng, Weile Jia, Mohan Chen, Guolin Ke, Weinan E, Linfeng Zhang, Han Wang

**Coalescence of immiscible droplets in liquid environments. (arXiv:2312.15500v1 [physics.flu-dyn])**

Huadan Xu, Tianyou Wang, Zhizhao Che

**Crafting crystalline topological insulators via accidental mode degeneracies. (arXiv:2312.15529v1 [physics.optics])**

Konstantin Rodionenko, Maxim Mazanov, Maxim A. Gorlach

**Bridging Rokhsar-Kivelson Type and Generic Quantum Phase Transitions via Thermofield Double States. (arXiv:2312.15530v1 [cond-mat.str-el])**

Wen-Tao Xu, Rui-Zhen Huang, Guang-Ming Zhang

**Inverse Measurements in Active Nematics. (arXiv:2312.15553v1 [cond-mat.soft])**

Aleix Boquet-Pujadas, Jérôme Hardouïn, Junhao Wen, Jordi Ignés-Mullol, Francesc Sagués

**Relativistic artificial molecules with tunable coupling and orbitals. (arXiv:2312.15570v1 [cond-mat.mes-hall])**

Xiao-Feng Zhou, Yu-Chen Zhuang, Mo-Han Zhang, Hao Sheng, Qing-Feng Sun, Lin He

**Field-induced transformation between triangular and square skyrmion crystals in a tetragonal polar magnet. (arXiv:2312.15587v1 [cond-mat.str-el])**

Satoru Hayami

**Planar Hall effect from superconducting fluctuations. (arXiv:2312.15688v1 [cond-mat.supr-con])**

L. Attias, K. Michaeli, M. Khodas

**Shell-shaped quantum droplet in a three-component ultracold Bose gas. (arXiv:2312.15846v1 [cond-mat.quant-gas])**

Yinfeng Ma, Tin-Lun Ho, Xiaoling Cui

**Discovery of a topological exciton insulator with tunable momentum order. (arXiv:2312.15862v1 [cond-mat.str-el])**

Md Shafayat Hossain, Tyler A. Cochran, Yu-Xiao Jiang, Songbo Zhang, Huangyu Wu, Xiaoxiong Liu, Xiquan Zheng, Byunghoon Kim, Guangming Cheng, Qi Zhang, Maksim Litskevich, Junyi Zhang, Zi-Jia Cheng, Jinjin Liu, Jia-Xin Yin, Xian P. Yang, Jonathan Denlinger, Massimo Tallarida, Ji Dai, Elio Vescovo, Anil Rajapitamahuni, Hu Miao, Nan Yao, Yingying Peng, Yugui Yao, Zhiwei Wang, Luis Balicas, Titus Neupert, M. Zahid Hasan

**Collisions of Majorana Zero Modes. (arXiv:2312.15878v1 [cond-mat.quant-gas])**

Liang-Liang Wang, Wenjun Shao, Jian Li

**Optical absorption tensors based on C$_{70}$ trimers and polymers. (arXiv:2312.15882v1 [cond-mat.mes-hall])**

Elnaz Rostampour, Badie Ghavami, Karin Larsson

**Discovery of acousto-drag photovoltaic effect. (arXiv:2312.15939v1 [cond-mat.mes-hall])**

Jiaming Gu, Yicheng Mou, Jianwen Ma, Haonan Chen, Chuanxin Zhang, Yuxiang Wang, Jiayu Wang, Hangwen Guo, Wu Shi, Xiang Yuan, Xue Jiang, Dean Ta, Jian Shen, Cheng Zhang

**Direct observation of topological magnon polarons in a multiferroic material. (arXiv:2312.15943v1 [cond-mat.str-el])**

Song Bao, Zhao-Long Gu, Yanyan Shangguan, Zhentao Huang, Junbo Liao, Xiaoxue Zhao, Bo Zhang, Zhao-Yang Dong, Wei Wang, Ryoichi Kajimoto, Mitsutaka Nakamura, Tom Fennell, Shun-Li Yu, Jian-Xin Li, Jinsheng Wen

**Gauging of generalized symmetry. (arXiv:2312.15958v1 [cond-mat.str-el])**

Tian Lan, Gen Yue, Longye Wang

**Perspective on nanoscale magnetic sensors using giant anomalous Hall effect in topological magnetic materials for read head application in magnetic recording. (arXiv:2312.15977v1 [cond-mat.mtrl-sci])**

Tomoya Nakatani, Prabhanjan D. Kulkarni, Hirofumi Suto, Keisuke Masuda, Hitoshi Iwasaki, Yuya Sakuraba

**Four-dimensional Floquet topological insulator with an emergent second Chern number. (arXiv:2312.16013v1 [cond-mat.mes-hall])**

Zheng-Rong Liu, Rui Chen, Bin Zhou

**Tensile strain induced brightening of momentum forbidden dark exciton in WS$_2$. (arXiv:2312.16041v1 [cond-mat.mes-hall])**

Tamaghna Chowdhury, Sagnik Chatterjee, Dibyasankar Das, Ivan Timokhin, Pablo Díaz Núñez, Gokul M. A., Suman Chatterjee, Kausik Majumdar, Prasenjit Ghosh, Artem Mishchenko, Atikur Rahman

**Robust $T$-Linear Resistivity due to SU(4) Valley + Spin Fluctuation Mechanism in Magic Angle Twisted Bilayer Graphene. (arXiv:2312.16042v1 [cond-mat.str-el])**

Daisuke Inoue, Seiichiro Onari, Hiroshi Kontani

**Intrinsic and extrinsic anomalous transport properties in noncollinear antiferromagnetic Mn$_3$Sn from first-principle calculations. (arXiv:2312.16050v1 [cond-mat.mtrl-sci])**

Xiuxian Yang, Wanxiang Feng, Xiaodong Zhou, Yuriy Mokrousov, Yugui Yao

**Ternary Alkali Metal Copper Chalcogenides ACuX (A= Na, K and X= S, Se, Te): Promising Candidate for Solar Harvesting Applications. (arXiv:2312.16063v1 [cond-mat.mtrl-sci])**

Gurudayal Behera, Surabhi Suresh Nair, Nirpendra Singh, K. R. Balasubramaniam, Aftab Alam

**The nature of low-temperature spin-freezing in frustrated Kitaev magnets. (arXiv:2312.16096v1 [cond-mat.str-el])**

U. Jena, P. Khuntia

**Dynamical polarization function, plasmons, their damping and collective effects in semi-Dirac bands. (arXiv:2312.16117v1 [cond-mat.mes-hall])**

Gabrielle Ross-Harvey, Andrii Iurov, Liubov Zhemchuzhna, Godfrey Gumbs, Danhong Huang

**Photoinduced metallic Volkov-Pankratov states in semi-Dirac material. (arXiv:2312.16120v1 [cond-mat.mes-hall])**

SK Firoz Islam

**Magnetic vortex control with current-induced axial magnetization in centrosymmetric Weyl materials. (arXiv:2312.16122v1 [cond-mat.mes-hall])**

J. G. Yang, Yaroslav Tserkovnyak, D. A. Pesin

**Large composite fermion effective mass at filling factor 5/2. (arXiv:2312.16135v1 [cond-mat.mes-hall])**

M. Petrescu, Z. Berkson-Korenberg, Sujatha Vijayakrishnan, K. W. West, L. N. Pfeiffer, G. Gervais

**Andreev bound states in superconductor-barrier-superconductor junctions of Rarita-Schwinger-Weyl semimetals. (arXiv:2312.16164v1 [cond-mat.supr-con])**

Ipsita Mandal

**Double and Quadruple Flat Bands tuned by Alternative magnetic Fluxes in Twisted Bilayer Graphene. (arXiv:2210.13976v2 [cond-mat.str-el] UPDATED)**

Congcong Le, Qiang Zhang, Cui Fan, Xianxin Wu, Ching-Kai Chiu

**Multiferroicity and Topology in Twisted Transition Metal Dichalcogenides. (arXiv:2210.14918v3 [cond-mat.str-el] UPDATED)**

Ahmed Abouelkomsan, Emil J. Bergholtz, Shubhayu Chatterjee

**Vibrational and thermal properties of amorphous alumina from first principles. (arXiv:2303.08637v2 [cond-mat.mtrl-sci] UPDATED)**

Angela F. Harper, Kamil Iwanowski, William C. Witt, Mike C. Payne, Michele Simoncelli

**Dynamical criticality of magnetization transfer in integrable spin chains. (arXiv:2303.16691v5 [cond-mat.stat-mech] UPDATED)**

Žiga Krajnik, Johannes Schmidt, Enej Ilievski, Tomaž Prosen

**Tuned gap in graphene through laser barrier. (arXiv:2303.17092v2 [cond-mat.mes-hall] UPDATED)**

Hasna Chnafa, Miloud Mekkaoui, Ahmed Jellal, Abdelhadi Bahaoui

**Role of effective mass anisotropy in realizing a hybrid nodal-line fermion state. (arXiv:2304.13086v3 [cond-mat.mtrl-sci] UPDATED)**

Bikash Patra, Rahul Verma, Shin-Ming Huang, Bahadur Singh

**Factors affecting the topological Hall effect in strongly correlated layered magnets: spin of the magnetic atoms, polar and azimuthal angle subtended by the spin texture. (arXiv:2305.13423v3 [cond-mat.mes-hall] UPDATED)**

Kaushal Kumar Kesharpu

**Transport properties of hybrid single-bilayer graphene interfaces in magnetic field. (arXiv:2305.14284v2 [cond-mat.mes-hall] UPDATED)**

Nadia Benlakhouy, Ahmed Jellal, Michael Schreiber

**Dynamic structure factor of two-dimensional Fermi superfluid with Rashba spin-orbit coupling. (arXiv:2306.05868v2 [cond-mat.quant-gas] UPDATED)**

Huaisong Zhao, Xu Yan, Shi-Guo Peng, Peng Zou

**Transport properties in gapped graphene through magnetic barrier in a laser field. (arXiv:2307.03999v2 [cond-mat.mes-hall] UPDATED)**

Rachid El Aitouni, Miloud Mekkaoui, Ahmed Jellal, Michael Schreiber

**Long-Range Attraction between Graphene and Water/Oil Interfaces. (arXiv:2307.15658v2 [cond-mat.soft] UPDATED)**

Avishi Abeywickrama, Douglas H. Adamson, Hannes C. Schniepp

**First-principle study of spin transport property in $L1_0$-FePd(001)/graphene heterojunction. (arXiv:2308.02171v4 [cond-mat.mtrl-sci] UPDATED)**

Hayato Adachi, Ryuusuke Endo, Hikari Shinya, Hiroshi Naganuma, Mitsuharu Uemoto

**Generalized Majorana edge modes in a number-conserving periodically driven $p$-wave superconductor. (arXiv:2309.01163v2 [cond-mat.mes-hall] UPDATED)**

Raditya Weda Bomantara

**Confinement twists achiral liquid crystals and causes chiral liquid crystals to twist in the opposite handedness: Cases in and around sessile droplets. (arXiv:2309.14242v2 [cond-mat.soft] UPDATED)**

Jungmyung Kim, Joonwoo Jeong

**Topological interfaces crossed by defects and textures of continuous and discrete point group symmetries in spin-2 Bose-Einstein condensates. (arXiv:2309.17394v2 [cond-mat.quant-gas] UPDATED)**

Giuseppe Baio, Matthew T. Wheeler, David S. Hall, Janne Ruostekoski, Magnus O. Borgh

**Majorana Fermion Mean-Field Theories of Kitaev Quantum Spin Liquids. (arXiv:2310.10230v2 [cond-mat.str-el] UPDATED)**

Shahnam Ghanbari Saheli, Jennifer Lin, Huanzhi Hu, Frank Krüger

**Method of Mechanical Exfoliation of Bismuth with Micro-Trench Structures. (arXiv:2311.01321v2 [cond-mat.mes-hall] UPDATED)**

Oulin Yu, Raphaela Allgayer, Simon Godin, Jacob Lalande, Paolo Fossati, Chunwei Hsu, Thomas Szkopek, Guillaume Gervais

**Single-Phase L1$_{0}$-Ordered High Entropy Thin Films with High Magnetic Anisotropy. (arXiv:2311.06618v2 [cond-mat.mtrl-sci] UPDATED)**

Willie B. Beeson, Dinesh Bista, Huairuo Zhang, Sergiy Krylyuk, Albert Davydov, Gen Yin, Kai Liu

**Hydrogen Doping Induced $p_x\pm ip_y$ Triplet Superconductivity in Quasi-One-Dimensional K$_2$Cr$_3$As$_3$. (arXiv:2311.10942v2 [cond-mat.supr-con] UPDATED)**

Ming Zhang, Chen Lu, Yajiang Chen, Yunbo Zhang, Fan Yang

**Gauging Non-Invertible Symmetries: Topological Interfaces and Generalized Orbifold Groupoid in 2d QFT. (arXiv:2311.17044v2 [hep-th] UPDATED)**

Oleksandr Diatlyk, Conghuan Luo, Yifan Wang, Quinten Weller

**Fermionic quartet and vestigial gravity. (arXiv:2312.09435v2 [cond-mat.other] UPDATED)**

G.E. Volovik

**Exposing the odd-parity superconductivity in CeRh$_2$As$_2$ with hydrostatic pressure. (arXiv:2312.09729v3 [cond-mat.supr-con] UPDATED)**

Konstantin Semeniuk, Meike Pfeiffer, Javier F. Landaeta, Michael Nicklas, Christoph Geibel, Manuel Brando, Seunghyun Khim, Elena Hassinger

**A solvable two-dimensional swarmalator model. (arXiv:2312.10178v2 [nlin.AO] UPDATED)**

Kevin O'Keeffe, Gourab Kumar Sar, Md Sayeed Anwar, Joao U. F. Lizárraga, Marcus A. M. de Aguiar, Dibakar Ghosh

**Extracting topological orders of generalized Pauli stabilizer codes in two dimensions. (arXiv:2312.11170v2 [quant-ph] UPDATED)**

Zijian Liang, Yijia Xu, Joseph T. Iosue, Yu-An Chen

**Family Puzzle, Framing Topology, $c_-=24$ and 3(E8)$_1$ Conformal Field Theories: 48/16 = 45/15 = 24/8 =3. (arXiv:2312.14928v1 [hep-th] CROSS LISTED)**

Juven Wang

Found 5 papers in prb We study the quench and the ramp dynamics of interacting $N$-component charged bosons with dipole symmetry using Schwinger-Keldysh field theory in the large-$N$ limit. The equilibrium phase diagram of these bosons shows two phases in the large-$N$ limit. The first is a normal phase where both the gl… Beginning from the conventional square-lattice nearest-neighbor antiferromagnetic Heisenberg model, we allow the ${J}_{x}$ and ${J}_{y}$ couplings to be anisotropic, with their values depending on the bond orientation. The emergence of anisotropic, bond-dependent couplings should be expected to occu… The creation of moiré superlattices in twisted bilayers of two-dimensional crystals has been utilized to engineer quantum material properties in graphene and transition metal dichalcogenide semiconductors. Here, we examine the structural relaxation and electronic properties in small-angle twisted bi… We study a class of multiorbital models based on those proposed by Venderbos Ideal Weyl semimetals, with minimum Weyl nodes located far away from each other in reciprocal space and near the Fermi level in the energy space, are considered to be crucial for revealing the intrinsic physical properties of Weyl semimetals. Based on first-principles calculations, we demonstrate th…

Date of feed: Wed, 27 Dec 2023 04:16:57 GMT**Search terms: **(topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)|(flatband)|(flat.{1}band)|(LK.{1}99) **Nonequilibrium dynamics of bosons with dipole symmetry: Large-$N$ Keldysh approach**

Md Mursalin Islam, K. Sengupta, and Rajdeep Sensarma

Author(s): Md Mursalin Islam, K. Sengupta, and Rajdeep Sensarma

[Phys. Rev. B 108, 214314] Published Tue Dec 26, 2023

**Quantum Weyl-Heisenberg antiferromagnet**

Peter Rosenberg and Efstratios Manousakis

Author(s): Peter Rosenberg and Efstratios Manousakis

[Phys. Rev. B 108, 214431] Published Tue Dec 26, 2023

**Moiré superstructures in marginally twisted ${\mathrm{NbSe}}_{2}$ bilayers**

James G. McHugh, Vladimir V. Enaldiev, and Vladimir I. Fal'ko

Author(s): James G. McHugh, Vladimir V. Enaldiev, and Vladimir I. Fal'ko

[Phys. Rev. B 108, 224111] Published Tue Dec 26, 2023

**Nematic order in topological Sachdev-Ye-Kitaev models**

Andrew Hardy, Anjishnu Bose, and Arun Paramekanti

Author(s): Andrew Hardy, Anjishnu Bose, and Arun Paramekanti*et al.* [Phys. Rev. B **98**, 235160 (2018)] which exhibit an interplay of topology, interactions, and fermion incoherence. In the noninteracting limit, these models exhibit trivial and Chern insulator phases with Chern number $…

[Phys. Rev. B 108, 235169] Published Tue Dec 26, 2023

**Complete topological phase diagram and realization of minimum Weyl nodes in a sheared chiral crystal of elemental tellurium**

Shuai Fan, Botao Fu, Da-Shuai Ma, and Rui Wang

Author(s): Shuai Fan, Botao Fu, Da-Shuai Ma, and Rui Wang

[Phys. Rev. B 108, 235211] Published Tue Dec 26, 2023

Found 2 papers in prl Molecular lattice clocks enable the search for new physics, such as fifth forces or temporal variations of fundamental constants, in a manner complementary to atomic clocks. Blackbody radiation (BBR) is a major contributor to the systematic error budget of conventional atomic clocks and is notorious… Kekulé-O order in graphene, which has recently been realized experimentally, induces Dirac electron masses on the order of $m∼100\text{ }\text{ }\mathrm{meV}$. We show that twisted bilayer graphene in which one or both layers have Kekulé-O order exhibits nontrivial flat electronic bands on honeycomb…

Date of feed: Wed, 27 Dec 2023 04:16:54 GMT**Search terms: **(topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)|(flatband)|(flat.{1}band)|(LK.{1}99) **Accurate Determination of Blackbody Radiation Shifts in a Strontium Molecular Lattice Clock**

B. Iritani, E. Tiberi, W. Skomorowski, R. Moszynski, M. Borkowski, and T. Zelevinsky

Author(s): B. Iritani, E. Tiberi, W. Skomorowski, R. Moszynski, M. Borkowski, and T. Zelevinsky

[Phys. Rev. Lett. 131, 263201] Published Tue Dec 26, 2023

**Twistronics of Kekulé Graphene: Honeycomb and Kagome Flat Bands**

Michael G. Scheer and Biao Lian

Author(s): Michael G. Scheer and Biao Lian

[Phys. Rev. Lett. 131, 266501] Published Tue Dec 26, 2023

Found 1 papers in prx Quantum fluids of light are coupled to their environments. A joint theory-experiment analysis shows this environment includes the thermal vibrations of the lattice hosting the fluid.

Date of feed: Wed, 27 Dec 2023 04:16:55 GMT**Search terms: **(topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)|(flatband)|(flat.{1}band)|(LK.{1}99) **Bogoliubov Excitations Driven by Thermal Lattice Phonons in a Quantum Fluid of Light**

Irénée Frérot, Amit Vashisht, Martina Morassi, Aristide Lemaître, Sylvain Ravets, Jacqueline Bloch, Anna Minguzzi, and Maxime Richard

Author(s): Irénée Frérot, Amit Vashisht, Martina Morassi, Aristide Lemaître, Sylvain Ravets, Jacqueline Bloch, Anna Minguzzi, and Maxime Richard

[Phys. Rev. X 13, 041058] Published Tue Dec 26, 2023

Found 3 papers in pr_res We formulate a theoretical approach to describe photon vortex production in synchrotron/cyclotron radiation from a helical moving electron under a uniform magnetic field in the relativistic quantum framework. In quantum theory, electron orbitals in a magnetic field are under Landau states. The Landa… Few-layer (FL) transition metal dichalcogenides have been found to exhibit discrete subbands, called van der Waals quantum well (vdWQW) states, resulting from out-of-plane quantum confinement. In this study, we reveal the twisted-resonant tunneling characteristics of a vdWQW device using a three-lay… A strong ultraviolet pumping laser propagating through the atmosphere could activate the medium and produce the forward and backward coherent air lasing. In this work, we present the theoretical analyses of forward and backward lasing dynamics in the long gain medium consisting of oxygen atoms. By n…

Date of feed: Wed, 27 Dec 2023 04:16:55 GMT**Search terms: **(topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)|(flatband)|(flat.{1}band)|(LK.{1}99) **Photon vortex generation by synchrotron radiation experiments in relativistic quantum approach**

Tomoyuki Maruyama, Takehito Hayakawa, Ryoichi Hajima, Toshitaka Kajino, and Myung-Ki Cheoun

Author(s): Tomoyuki Maruyama, Takehito Hayakawa, Ryoichi Hajima, Toshitaka Kajino, and Myung-Ki Cheoun

[Phys. Rev. Research 5, 043289] Published Tue Dec 26, 2023

**Polarity-dependent twist-controlled resonant tunneling device based on few-layer $\mathrm{W}{\mathrm{Se}}_{2}$**

Kei Kinoshita, Rai Moriya, Shota Okazaki, Yijin Zhang, Satoru Masubuchi, Kenji Watanabe, Takashi Taniguchi, Takao Sasagawa, and Tomoki Machida

Author(s): Kei Kinoshita, Rai Moriya, Shota Okazaki, Yijin Zhang, Satoru Masubuchi, Kenji Watanabe, Takashi Taniguchi, Takao Sasagawa, and Tomoki Machida

[Phys. Rev. Research 5, 043292] Published Tue Dec 26, 2023

**Propagation effects of seeded collective emission by two-photon excited oxygen atoms**

Xin Wang, Yu-Hung Kuan, Jun Jie Cui, Yu Kun Yang, Fan Xing, Wen-Te Liao, Luqi Yuan, Yongjun Cheng, Zeyang Liao, Zheng Li, and Song Bin Zhang

Author(s): Xin Wang, Yu-Hung Kuan, Jun Jie Cui, Yu Kun Yang, Fan Xing, Wen-Te Liao, Luqi Yuan, Yongjun Cheng, Zeyang Liao, Zheng Li, and Song Bin Zhang

[Phys. Rev. Research 5, 043293] Published Tue Dec 26, 2023