Found 57 papers in cond-mat We investigate the influence of field-like torque and the direction of the
external magnetic field on a one-dimensional array of serially connected
spin-torque nano oscillators, having free layers with perpendicular anisotropy,
to achieve complete synchronization between them by analyzing the associated
Landau-Lifshitz-Gilbert-Slonczewski equation. The obtained results for
synchronization are discussed for the cases of 2, 10 and 100 oscillators
separately. The roles of the field-like torque and the direction of the
external field on the synchronization of the STNOs are explored through the
Kuramoto order parameter. While the field-like torque alone is sufficient to
bring out global synchronization in the system made up of a small number of
STNOs, the direction of the external field is also needed to be slightly tuned
to synchronize the one-dimensional array of a large number of STNOs. The
formation of complete synchronization through the construction of clusters
within the system is identified for the 100 oscillators. The large amplitude
synchronized oscillations are obtained for small to large numbers of
oscillators. Moreover, the tunability in frequency for a wide range of currents
is shown for the synchronized oscillations up to 100 spin-torque oscillators.
In addition to achieving synchronization, the field-like torque increases the
frequency of the synchronized oscillations. The transverse Lyapunov exponents
are deduced to confirm the stable synchronization in coupled STNOs due to the
field-like torque and to validate the results obtained in the numerical
simulations. The output power of the array is estimated to be enhanced
substantially due to complete synchronization by the combined effect of
field-like torque and tunability of the field angle.
We present a study of electrical and thermal transport in Weyl semimetal
WTe$_2$ down to 0.3 K. The Wiedemann-Franz law holds below 2 K and a downward
deviation starts above. The deviation is more pronounced in cleaner samples, as
expected in the hydrodynamic picture of electronic transport, where a fraction
of electron-electron collisions conserve momentum. Phonons are the dominant
heat carriers and their mean-free-path do not display a Knudsen minimum. This
is presumably a consequence of weak anharmonicity, as indicated by the
temperature dependence of the specific heat. Frequent momentum exchange between
phonons and electrons leads to quantum oscillations of the phononic thermal
conductivity. Bloch-Gr\"uneisen picture of electron-phonon scattering breaks
down at low temperature when Umklapp ph-ph collisions cease to be a sink for
electronic flow of momentum. Comparison with semi-metallic Sb shows that normal
ph-ph collisions are amplified by anharmonicity. In both semimetals, at
cryogenic temperature, e-ph collisions degrade the phononic flow of energy but
not the electronic flow of momentum.
Landauer's principle states that erasing a bit of information at fixed
temperature T costs at least kT ln 2 units of work. Here we investigate erasure
at varying temperature, to which Landauer's result does not apply. We formulate
bit erasure as a stochastic nonequilibrium process involving a compression of
configuration space, with physical and logical states associated in a symmetric
way. Erasure starts and ends at temperature T, but temperature can otherwise
vary with time in an arbitrary way. Defined in this way, erasure is governed by
a set of nonequilibrium fluctuation relations that show that
varying-temperature erasure can done with less work than k T ln 2. As a result,
erasure and the complementary process of bit randomization can be combined to
form a work-producing engine cycle.
Klein's paradox refers to the transmission of a relativistic particle through
a high potential barrier. Although it has a simple resolution in terms of
particle-to-antiparticle tunneling (Klein tunneling), debates on its physical
meaning seem lasting partially due to the lack of direct experimental
verification. In this article, we point out that honeycomb-type photonic
crystals (PhCs) provide an ideal platform to investigate the nature of Klein
tunneling, where the effective Dirac mass can be tuned in a relatively easy way
from a positive value (trivial PhC) to a negative value (topological PhC) via a
zero-mass case (PhC graphene). Especially, we show that analysis of the
transmission between domains with opposite Dirac masses -- a case hardly be
treated within the scheme available so far -- sheds new light on the
understanding of the Klein tunneling.
We derive new dualities of topological quantum field theories in three
spacetime dimensions that generalize the familiar level-rank dualities of
Chern-Simons gauge theories. The key ingredient in these dualities is
non-abelian anyon condensation, which is a gauging operation for topological
lines with non-group-like i.e. non-invertible fusion rules. We find that,
generically, dualities involve such non-invertible anyon condensation and that
this unifies a variety of exceptional phenomena in topological field theories
and their associated boundary rational conformal field theories, including
conformal embeddings, and Maverick cosets (those where standard algorithms for
constructing a coset model fail.) We illustrate our discussion in a variety of
isolated examples as well as new infinite series of dualities involving
non-abelian anyon condensation including: i) a new description of the
parafermion theory as $(SU(N)_{2} \times Spin(N)_{-4})/\mathcal{A}_{N},$ ii) a
new presentation of a series of points on the orbifold branch of $c=1$
conformal field theories as $(Spin(2N)_{2} \times Spin(N)_{-2} \times
Spin(N)_{-2})/\mathcal{B}_{N}$, and iii) a new dual form of $SU(2)_{N}$ as
$(USp(2N)_{1} \times SO(N)_{-4})/\mathcal{C}_{N}$ arising from conformal
embeddings, where $\mathcal{A}_{N}, \mathcal{B}_{N},$ and $\mathcal{C}_{N}$ are
appropriate collections of gauged non-invertible bosons.
Effective control of terahertz radiation requires the development of
efficient and fast modulators with a large modulation depth. This challenge is
often tackled by using metamaterials, artificial sub-wavelength optical
structures engineered to resonate at the desired terahertz frequency.
Metamaterial-based devices exploiting graphene as the active tuneable element
have been proven to be a highly effective solution for THz modulation. However,
whilst the graphene conductivity can be tuned over a wide range, it cannot be
reduced to zero due to the gapless nature of graphene, which directly limits
the maximum achievable modulation depth for single-layer metamaterial
modulators. Here, we demonstrate two novel solutions to circumvent this
restriction: Firstly, we excite the modulator from the back of the substrate,
and secondly, we incorporate air gaps into the graphene patches. This results
in a ground-breaking graphene-metal metamaterial terahertz modulator, operating
at 2.0-2.5 THz, which demonstrates a 99.01 % amplitude and a 99.99 % intensity
modulation depth at 2.15 THz, with a reconfiguration speed in excess of 3 MHz.
Our results open up new frontiers in the area of terahertz technology.
We study the convergence of the Ginzburg-Landau (GL) expansion in the context
of the Bardeen-Cooper-Schrieffer (BCS) theory for superconductivity and the
Nambu-Jona-Lasinio (NJL) model for chiral symmetry breaking at finite
temperature $T$ and chemical potential $\mu$. We present derivations of the
all-order formulas for the coefficients of the GL expansions in both systems
under the mean-field approximation. We show that the convergence radii for the
BCS gap $\Delta$ and dynamical quark mass $M$ are given by $\Delta_\text{conv}
= \pi T$ and $M_\text{conv} = \sqrt{\mu^2 + (\pi T)^2}$, respectively. We also
discuss the implications of these results and the quantitative reliability of
the GL expansion near the first-order chiral phase transition.
Quaternary chalcogenide compositions have been broadly explored due to their
promising potential for various optoelectronic applications. The band
structure, density of states and optical properties of CuZn2InS4 and CuZn2GaS4
for kesterite and stannite structures were studied with full potential
augmented plane wave method (FP-LAPW) via Wien2k code. The total energy in
equilibrium was calculated for different possible crystal structures and their
phase stability, and transitions with p-d orbitals were analyzed. The
absorption coefficient, dielectric function, and refractive index of these
materials were also explored within a broad range of energy. We compared the
calculated band gap values with available experimental results.
The magnetic Weyl semimetal Co3Sn2S2 is extensively investigated due to its
giant anomalous Hall effect (AHE).Recent studies demonstrate that the AHE can
be effectively tuned by multi-electron Ni doping.To reveal the underlying
mechanism of this significant manipulation,it is crucial to explore the band
structure modification caused by Ni doping.Here,we study the electrodynamics of
both pristine and Ni-doped Co3-xNixSn2S2 with x=0, 0.11 and 0.17 by infrared
spectroscopy. We find that the inverted energy gap around the Fermi level(EF)
gets smaller at x=0.11,which is supposed to enhance the Berry curvature and
therefore increase the AHE.Then EF moves out of this gap at
x=0.17.Additionally,the low temperature carrier density is demonstrated to
increase monotonically upon doping,which is different from previous Hall
measurement results. We also observe the evidences of band broadening and
exotic changes of high-energy interband transitions caused by doping.Our
results provide detailed information about the band structure of Co3-xNixSn2S2
at different doping levels,which will help to guide further studies on the
chemical tuning of AHE.
Symmetry-breaking quantum phase transitions lead to the production of
topological defects or domain walls in a wide range of physical systems. In
second-order transitions, these exhibit universal scaling laws described by the
Kibble-Zurek mechanism, but for first-order transitions a similarly universal
approach is still lacking. Here we propose a spinor Bose-Einstein condensate as
a testbed system where critical scaling behavior in a first-order quantum phase
transition can be understood from generic properties. We generalize the
Kibble-Zurek mechanism to determine the critical exponents for: (1) the onset
of the decay of the metastable state on short times scales, and (2) the number
of resulting phase-separated ferromagnetic domains at longer times, as a
one-dimensional spin-1 condensate is ramped across a first-order quantum phase
transition. The predictions are in excellent agreement with mean-field
numerical simulations and provide a paradigm for studying the decay of
metastable states in experimentally accessible systems.
The role of anyonic statistics stands as a cornerstone in the landscape of
topological quantum techniques. While recent years have brought forth
encouraging and persuasive strides in detecting anyons, a significant facet
remains unexplored, especially in view of connecting anyonic physics to quantum
information platforms-whether and how entanglement can be generated by anyonic
braiding. Here, we demonstrate that even if the two anyonic subsystems are
connected only by electron tunneling, anyonic entanglement, manifesting
fractional statistics, is generated. Specifically, we address this question for
fractional quantum Hall edges bridged by a quantum point contact that allows
only transmission of fermions (so-called Andreev-like tunneling), invoking the
physics of two-beam collisions in an anyonic Hong-Ou-Mandel collider We define
an entanglement pointer-a current-noise-based function tailored to quantify
entanglement and show that it reflects the role of quasiparticle statistics. A
striking feature of our statistics-induced-entanglement pointer is its relative
resilience to entanglement stemming from electrostatic interactions between the
two anyonic subsystems.
Local geometrical features of a porous material such as the shape and size of
a pore or the curvature of a solid ligament often affect the macroscopic
properties of the material, and their characterization is necessary to fully
understand the structure-property relationships.In this contribution, we
present an approach to automatically segment large porous structures into such
local features. Our work takes inspiration from techniques available in
Topological Data Analysis(TDA).In particular, using Morse theory, we generate
Morse-Smale Complexes(MSC) of our structures that segment the structure, and/or
its porosity into individual features that can then be compared. We develop a
tool that is built on the topology toolkit (TTK) library, an open source
platform for the topological analysis of scalar data, with which we can perform
segmentation of these structures. Our tool takes a volumetric grid
representation as an input, which can be generated from atomistic or mesh
structure models and any function defined on such grid, e.g. the distance to
the surface or the interaction energy with a probe. We demonstrate the
applicability of the tool by two examples related with analysis of porosity in
zeolite materials as well as analysis of ligaments in a porous metal structure.
Specifically, by segmenting the pores in the structure we demonstrate some
applications to zeolites such as assessing pore-similarity between structures
or evaluating the accessible volume to a target molecule such as methane that
can be adsorbed to its surface. Moreover, once the MSC's are generated, we can
construct graph representations of the void space, replacing the entire pore
structure by a simply connected graph. Similarly, the same tool is used to
segment and generate graphs representing the solid structure and we show how
they can be used to correlate structure and mechanical properties of the
material.
Thouless charge pump enables a quantized transport of charge through an
adiabatic evolution of the Hamiltonian exhibiting topological phase. While this
charge pumping is known to be robust against the presence of weak disorder in
the system, it often breaks down with the increase in disorder strength. In
this work, however, we show that in a one dimensional Su-Schrieffer-Heeger
lattice, a unit cell-wise staggered quasiperiodic disorder favors a quantized
charge pump. Moreover, we show that such quantized Thouless charge pump is
achieved by following the standard single cycle pumping protocol which usually
leads to a breakdown of charge pump in other known models. This unusual
property is found to be due to an emergence of a trivial gapped phase from a
topological phase as the quasiperiodic disorder is tuned. This emergent gapped
to gapped transition also allows us to propose a non-standard pumping scheme
where a modulated disorder favors a quantized Thouless charge pump.
The study investigates the density, phase composition, microstructure and
mechanical properties (microhardness, fracture toughness) of binderless WC +
SiC and WC + SiC + C ceramics obtained by Spark Plasma Sintering (SPS).
Nanopowders of a-WC produced by DC arc plasma chemical synthesis were used as
raw materials. Powder compositions for sintering contained graphite (0.3, 0.5%
wt.) or b-SiC (1, 3, 5% wt.) with 0.3% wt. graphite. It was shown that WC + 1%
wt. SiC + 0.3% wt.C ceramics have a homogeneous fine-grained microstructure,
high relative density, increased microhardness and Palmquist fracture toughness
(Indentation Fracture Resistance). The kinetics of the initial sintering stage
of WC + C and WC + C + SiC powder compositions was also analyzed using
high-temperature dilatometry at the conventional pressureless sintering (CPS)
conditions. The CPS and SPS activation energies of WC + SiC powder at the
intensive shrinkage stage were determined using the Young-Cutler model. The CPS
activation energies of WC, WC + C and WC + C + SiC powder compositions are
close to the activation energy of diffusion of the carbon C along the a-WC
grain boundaries. The SPS activation energies of WC + C and WC+ C + SiC powder
compositions turn out to be lower than the activation energy of the C of a-WC
grain boundary.
We consider a modified graphene model under exchange couplings. Various
quantum anomalous phases are known to emerge under uniform or staggered
exchange couplings. We introduce the twist between the orientations of two
sublattice exchange couplings, which is useful for examining how such
topologically nontrivial phases under different types of exchange couplings are
connected to one another. The phase diagrams constructed by the variation of
exchange coupling strengths and twist angles exhibit rich structures of
successive topological transitions. We analyze the emergence of peculiar phases
in terms of the evolution of the energy dispersions. Perturbation schemes
applied to the energy levels turn out to reproduce well phase boundary lines up
to moderate values of the twist angle. We also discover two close topological
transitions under uniform exchange couplings, which is attributed to the
interplay of the trigonal-warping deformation due to Rashba spin-orbit coupling
and the staggered sublattice potential. Finally the implications of Berry
curvature structure and topological excitations in real and pseudo spin
textures are discussed.
Topological defects are ubiquitous on surfaces with orientational order
fields. Here, we study equilibrium states generated by the feedback between
geometry and nematic order on fluid membranes with an integer topological
defect. When the Frank elastic constants associated with the orientational
field dominate, the surfaces spontaneously deform toward an conical shape
featuring an aster topological defect at its apex. In the case of vanishing
tension this is a solution to the normal force balance. We show that the
stability of the surface depends on the balance of the elastic parameters and
the phase of the defect. When boundary constraints are introduced, we observe
three distinct modes of deformation. These deformation modes take advantage of
the way in which splay, twist and bend distortions of the director field can be
exchanged on a curved surface. We discuss how these deformation modes are
distinguished by their response to the cost of twist distortions and the
existence of inverted solutions. Our findings show that fusion of +1/2
topological defect pairs can reduce the total energy of deformable surfaces.
Finally, we argue how these results can be relevant for biological systems.
Moir\'e superlattices have emerged as a new platform for studying strongly
correlated quantum phenomena, but these systems have been largely limited to
van der Waals layer two-dimensional (2D) materials. Here we introduce moir\'e
superlattices leveraging ultra-thin, ligand-free halide perovskites,
facilitated by ionic interactions. Square moir\'e superlattices with varying
periodic lengths are clearly visualized through high-resolution transmission
electron microscopy. Twist-angle-dependent transient photoluminescence
microscopy and electrical characterizations indicate the emergence of localized
bright excitons and trapped charge carriers near a twist angle of ~10{\deg}.
The localized excitons are accompanied by enhanced exciton emission, attributed
to an increased oscillator strength by a theoretically forecasted flat band.
This work illustrates the potential of extended ionic interaction in realizing
moir\'e physics at room temperature, broadening the horizon for future
investigations.
We investigate the phases and phase transitions of the disordered Haldane
model in the presence of on-site disorder. We use the real-space Chern marker
and transfer matrices to extract critical exponents over a broad range of
parameters. The disorder-driven transitions are consistent with the plateau
transitions in the Integer Quantum Hall Effect (IQHE), in conformity with
recent simulations of disordered Dirac fermions. Our numerical findings are
compatible with an additional line of mass-driven transitions with a
continuously varying correlation length exponent. The values interpolate
between free Dirac fermions and the IQHE with increasing disorder strength. We
also show that the fluctuations of the Chern marker exhibit a power-law
divergence in the vicinity of both sets of transitions, yielding another
varying exponent. We discuss the interpretation of these results.
Using first principle calculations we examine properties of (Cd,V)Te,
(Cd,Cr)Te, (Hg,V)Te, and (Hg,Cr)Te relevant to the quantum anomalous Hall
effect (QAHE), such as the position of V- and Cr- derived energy levels and the
exchange interactions between magnetic ions. We consider CdTe and HgTe,
containing 12.5% of cation-substitutional V or Cr ions in comparison to the
well-known case of (Cd,Mn)Te and (Hg,Mn)Te, and examine their suitability for
the fabrication of ferromagnetic barriers or ferromagnetic topological quantum
wells, respectively. To account for the strong correlation of transition metal
d electrons we employ hybrid functionals with different mixing parameters aHSE
focusing on aHSE = 0.32, which better reproduces the experimental band gaps in
HgTe, CdTe, Hg0.875Mn0.125Te, and Cd0.875Mn0.125Te. We find that Cr, like Mn,
acts as an isoelectronic dopant but V can be an in-gap donor in CdTe and a
resonant donor in HgTe, similar to the case of Fe in HgSe. From the magnetic
point of view, Cr-doping results in a ferromagnetic phase within the general
gradient approximation (GGA) but interactions become antiferromagnetic within
hybrid functionals. However, (Hg,V)Te is a ferromagnet within both
exchange-correlation functionals in a stark contrast to (Hg,Mn)Te for which
robust antiferromagnetic coupling is found theoretically and experimentally.
Furthermore, we establish that the Jahn-Teller effect is relevant only in the
case of Cr-doping. Considering lower defect concentrations in HgTe-based
quantum wells compared to (Bi,Sb)3Te2 layers, our results imply that HgTe
quantum wells or (Cd,Hg)Te barriers containing either V or Cr show advantages
over (Bi,Sb,Cr,V)3Te2-based QAHE systems but whether (i) ferromagnetic coupling
will dominate in the Cr case and (ii) V will not introduce too many electrons
to the quantum well is to be checked experimentally
Unexpected, yet useful functionalities emerge when two or more materials
merge coherently. Artificial oxide superlattices realize atomic and crystal
structures that are not available in nature, thus providing controllable
correlated quantum phenomena. This review focuses on 4d and 5d oxide
superlattices, in which the spin-orbit coupling plays a significant role
compared with conventional 3d oxide superlattices. Modulations in crystal
structures with octahedral distortion, phonon engineering, electronic
structures, spin orderings, and dimensionality control are discussed for 4d
oxide superlattices. Atomic and magnetic structures, Jeff = 1/2 pseudospin and
charge fluctuations, and the integration of topology and correlation are
discussed for 5d oxide superlattices. This review provides insights into how
correlated quantum phenomena arise from the deliberate design of superlattice
structures that give birth to novel functionalities.
Zero-dimensional graphene quantum dots (GQD) dispersed in conducting polymer
matrix display a striking range of optical, mechanical, and thermoelectric
properties which can be utilized to design next-generation sensors and low-cost
thermoelectric. This exotic electrical property in GQDs is achieved by
exploiting the concentration of the GQDs and by tailoring the functionalization
of the GQDs. However, despite extensive investigation, the nonlinear
resistivity behavior leading to memristive like characteristic has not been
explored much. Here, we report electrical characterisation of nitrogen
functionalized GQD (NGQD) embedded in a polyaniline (PANI) matrix. We observe a
strong dependence of the resistance on current and voltage history, the
magnitude of which depends on the NGQD concentration and temperature. We
explain this memristive property using a phenomenological model of the
alignment of PANI rods with a corresponding charge accumulation arising from
the NGQD on its surface. The NGQD-PANI system is unique in its ability to
matrix offers a unique pathway to design neuromorphic logic and synaptic
architectures with crucial advantages over existing systems.
We investigate collective spin excitations of graphene electrons with
short-ranged interactions and subject to the external Zeeman magnetic field. We
find that in addition to the familiar Silin spin wave, a collective spin-flip
excitation that reduces to the uniform precession when the wave's momentum
approaches zero, the magnetized graphene supports another collective mode
visible in the transverse spin susceptibility: a collective spin-current mode.
Unlike the Silin wave, this mode is not dictated by the spin-rotational
symmetry but rather owns its existence to the pseudo-spin structure of the
graphene lattice. We find the new collective excitation to become sharply
defined in a finite interval of wave's momenta, the range of which is
determined by the interaction and the magnetization.
It is now well established that a high-frequency electromagnetic dressing
field within the off-resonance regime significantly modifies the electronic
transport and optical properties on Dirac materials. Here, using light with
circular polarization, we investigate its effect on the energy spectrum of
tilted monolayer 1T$^\prime$MoS$_2$ which acquires two energy gaps associated
with up- and down- pseudospin. We can adjust its electronic properties over a
wider range by varying these two band gaps in contrast with graphene. With the
use of the Lindhard approach for the frequency-dependent polarizability
propagator, we have developed a rigorous theoretical formalism for employing
the Floquet energy spectrum for investigating the many-body effects on the
plasmon excitations, their lifetimes due to Landau damping and the exchange
energy of tilted monolayer 1T$^\prime$MoS$_2$ under normal incidence of
electromagnetic radiation at arbitrary temperature. The dressed states at very
low temperature corresponding to circular polarization suppress the response of
the system to the external probe. This gives rise to the weak but long lived
plasmon excitations at small wavenumber $q$ when compared to the plasmon
spectrum in this regime in the absence of irradiation. However,
$\sqrt{qT}$-dependent plasmons are restored at high temperatures. Our
calculations have shown that the tilting, anisotropy, direct and indirect band
gaps lead to a reduced exchange energy, which has some potential applications
such as, tunability of exciton polariton and plasmon excitations.
We uncover a new class of bound states in the continuum in bilayer graphene,
which emerges independent of symmetry protection or additional degrees of
freedom. Through a comparative analysis of AA- and AB-stacked bilayer graphene,
we demonstrate that these states originate from the intrinsic algebraic
structure of the Hamiltonian rather than any specific underlying symmetry. This
discovery paves the way for innovative approaches in defect and band-structure
engineering. We conclude with a proposed protocol for observing these states in
scanning tunneling microscopy experiments.
Carbon allotropes have vast potential in various applications, including
superconductivity, energy storage, catalysis, and photoelectric semiconductor
devices. Recently, there has been significant research interest in exploring
new carbon materials that exhibit unique electronic structures. Here, we
propose a novel two-dimensional (2D) carbon allotrope called TCH-SSH-2D, which
possesses a Dirac node-line (DNL) semimetallic state. The structure of
TCH-SSH-2D is derived from the TCH-type Archimedean polyhedral carbon cluster
units, combined with the SSH lattice model, possessing a space group of
tetragonal P4/mmm. Using first-principles calculations, we demonstrate that the
system is dynamically, thermodynamically, and mechanically stable. It exhibits
an energetically favorable structure with no imaginary frequency in the phonon
dispersion curves and elastic constants satisfying the Born-Huang stability
criterion. Our findings not only contribute to a deeper understanding of the
carbon allotrope family but also provide an opportunity to explore unique Dirac
states in two-dimensional pure carbon systems.
The relationship between the polymer orientation and the chaotic flow, in a
dilute solution of rigid rodlike polymers at low Reynolds number, is
investigated by means of direct numerical simulations. It is found that the
rods tend to align with the velocity field in order to minimize the friction
with the solvent fluid, while regions of rotational disorder are related to
strong vorticity gradients, and therefore to the chaotic flow. The
"turbulent-like" behavior of the system is therefore associated with the
emergence and interaction of topological defects of the mean director field,
similarly to active nematic turbulence. The analysis has been carried out in
both two and three spatial dimensions.
In gauge theories with fundamental matter there is typically no sharp way to
distinguish confining and Higgs regimes, e.g. using generalized global
symmetries acting on loop order parameters. It is standard lore that these two
regimes are continuously connected, as has been explicitly demonstrated in
certain lattice and continuum models. We point out that Higgsing and
confinement sometimes lead to distinct symmetry protected topological (SPT)
phases -- necessarily separated by a phase transition -- for ordinary global
symmetries. We present explicit examples in 3+1 dimensions, obtained by adding
elementary Higgs fields and Yukawa couplings to QCD while preserving parity P
and time reversal T. In a suitable scheme, the confining phases of these
theories are trivial SPTs, while their Higgs phases are characterized by
non-trivial P- and T-invariant theta-angles $\theta_f, \theta_g = \pi$ for
flavor or gravity background gauge fields, i.e. they are topological insulators
or superconductors. Finally, we consider conventional three-flavor QCD (without
elementary Higgs fields) at finite $U(1)_B$ baryon-number chemical potential
$\mu_B$, which preserves P and T. At very large $\mu_B$, three-flavor QCD is
known to be a completely Higgsed color superconductor that also spontaneously
breaks $U(1)_B$. We argue that this high-density phase is in fact a gapless
SPT, with a gravitational theta-angle $\theta_g = \pi$ that safely co-exists
with the $U(1)_B$ Nambu-Goldstone boson. We explain why this SPT motivates
unexpected transitions in the QCD phase diagram, as well as anomalous surface
modes at the boundary of quark-matter cores inside neutron stars.
The emergence of bulk carbon ferromagnetism is long-expected over years. At
nanoscale, carbon ferromagnetism was detected by analyzing the magnetic edge
states via scanning tunneling microscopy(STM), and its origin can be explained
by local redistribution of electron wave function. In larger scale, carbon
ferromagnetism can be created by deliberately producing defects in graphite,
and detected by macroscopic technical magnetization. Meanwhile, it becomes
crucial to determine that the detected magnetization is originated from carbon
rather than from magnetic impurities. One solution is X-ray magnetic circular
dichroism (XMCD). Nonetheless, a reproducible, full section of XMCD spectrum
across C-1s absorption energy has not appeared yet, which should be decisive
for assuring the indisputable existence of bulk carbon ferromagnetism. Besides,
the lack of direct observation on the atomic structure of the ferromagnetic
carbon leaves the structural origin of its ferromagnetism still in mist. In
this work, for detecting bulk carbon ferromagnetism, we managed to grow
all-carbon film consisting of vertically aligned graphene multi-edge (VGME),
which wove into a three-dimensional hyperfine-porous network. Magnetization
(M-H) curves and XMCD spectra co-confirmed bulk carbon ferromagnetism of VGME
at room temperature, with the average unit magnetic momentum of ~0.0006
miuB/atom. The influence of magnetic impurities on magnetization was excluded
by both absorption spectra and inductively coupled plasma mass spectrometry
measurements. The spin transfer behavior also verified the long-range and
robust feature of the bulk carbon ferromagnetism. Our work provides direct
evidence of elementary resolved bulk carbon ferromagnetism at room temperature
and clarifies its origin from pi-electrons at graphene edges.
We model the electronic properties of thin films of binary compounds with
stacked layers where each layer is a two-dimensional honeycomb lattice with two
atoms per unit cell. The two atoms per cell are assigned different onsite
energies in order to consider six different stacking orders: ABC, ABA, AA,
ABC$^{\prime}$, ABA$^{\prime}$, and AA$^{\prime}$. Using a minimal
tight-binding model with nearest-neighbor hopping, we consider whether a fault
in the texture of onsite energies in the vertical, stacking direction supports
localized states, and we find localized states within the bulk band gap for
ABC, ABA, and AA$^{\prime}$ stacking. Depending on the stacking type, parameter
values, and whether the soliton is atomically sharp or a smooth texture, there
are a range of different band structures including soliton bands that are
either isolated or that hybridize with other states, such as surface states,
and soliton bands that are either dispersive or flat, the latter yielding
narrow features in the density of states. We discuss the relevance of our
results to specific materials including graphene, hexagonal boron nitride and
other binary compounds.
The biphenylene network (BPN) has a unique two-dimensional atomic structure,
where hexagonal unit cells are arranged on a square lattice. Inspired by such a
BPN structure, we design a counterpart in the fashion of photonic crystals
(PhCs), which we refer to as the BPN PhC. We study the photonic band structure
using the finite element method and characterize the topological properties of
the BPN PhC through the use of the Wilson loop. Our findings reveal the
emergence of topological edge states in the BPN PhC, specifically in the zigzag
edge and the chiral edge, as a consequence of the nontrivial Zak phase in the
corresponding directions. In addition, we find the localization of
electromagnetic waves at the corners formed by the chiral edges, which can be
considered as second-order topological states, i.e., topological corner states.
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 occur
naturally in most antiferromagnetic compounds which undergo structural
transitions that reduce the point-group symmetry at lower temperature. Using
the spin-wave approximation, we study the model in several parameter regimes by
diagonalizing the reduced Hamiltonian exactly, and computing the edge spectrum
and Berry connection vector, which show clear evidence of localized topological
charges. We discover phases that exhibit Weyl-type spin-wave dispersion,
characterized by pairs of degenerate points and edge states, as well as phases
supporting lines of degeneracy. We also identify a parameter regime in which
there is an exotic state hosting gapless linear spin-wave dispersions with
different longitudinal and transverse spin-wave velocities.
Author email info: prosenberg15@gmail.com and manousakis@gmail.com
The discovery of superconductivity at 80 K under high pressure in
La$_3$Ni$_2$O$_7$ presents the groundbreaking confirmation that high-$T_c$
superconductivity is a property of strongly correlated materials beyond
cuprates. We use density functional theory (DFT) calculations of the band
structure of La$_3$Ni$_2$O$_7$ under pressure to verify that the low-energy
bands are composed almost exclusively of Ni 3$d_{x^2-y^2}$ and O 2$p$ orbitals.
We deduce that the Ni 3$d_{z^2}$ orbitals are essentially decoupled by the
geometry of the high-pressure structure and by the effect of the Ni Hund
coupling being strongly suppressed, which results from the enhanced interlayer
antiferromagnetic interaction between $d_{z^2}$ orbitals and the strong
intralayer hybridization of the $d_{x^2-y^2}$ orbitals with O 2$p$. By
introducing a tight-binding model for the Fermi surfaces and low-energy
dispersions, we arrive at a bilayer $t$-$t_\perp$-$J$ model with strong
interlayer hopping, which we show is a framework unifying La$_3$Ni$_2$O$_7$
with cuprate materials possessing similar band structures, particularly the
compounds La$_2$CaCu$_2$O$_6$, Pb$_2$Sr$_2$YCu$_3$O$_8$, and
EuSr$_2$Cu$_2$NbO$_8$. We use a renormalized mean-field theory to show that
these systems should have ($d$+$is$)-wave superconductivity, with a dominant
$d$-wave component and the high $T_c$ driven by the near-optimally doped
$\beta$ band, while the $\alpha$ band adds an $s$-wave component that should
lead to clear experimental signatures.
ScFe$_6$Ge$_4$ with the LiFe$_6$Ge$_4$-type structure (space group
$R{\bar{3}}m$), which has a double-layered kagome lattice (18$h$ site) of Fe
crystallographically equivalent to that of a well-known topological ferromagnet
Fe$_3$Sn$_2$, is newly found to be antiferromagnetic (AFM) with a high N\'eel
temperature of $T_{\rm{N}} \approx 650$ K, in contrast to the ferromagnetic
(FM) ground state previously proposed in a literature. $^{45}$Sc nuclear
magnetic resonance experiment revealed the absence of a hyperfine field at the
Sc site, providing microscopic evidence for the AFM state and indicating AFM
coupling between the bilayer kagome blocks. The stability of the AFM structure
under the assumption of FM intra-bilayer coupling is verified by DFT
calculations.
We consider a new class of topological defects in chiral magnetic crystals
such as FeGe and MnSi. These are composite topological defects that arise when
skyrmions in the magnetic order intersect with twin boundaries in the
underlying crystalline lattice. We show that the resulting stable
configurations are a new type of defect that can be viewed as half-hopfions.
This concise review aims to provide a summary of the most relevant recent
experimental and theoretical results for solitons, i.e., self-trapped bound
states of nonlinear waves, in two- and three-dimensional (2D and 3D) media. In
comparison with commonly known one-dimensional solitons, which are, normally,
stable modes, a challenging problem is the propensity of 2D and 3D solitons to
instability, caused by the occurrence of the critical or supercritical wave
collapse (catastrophic self-compression) in the same spatial dimension. A
remarkable feature of multidimensional solitons is their ability to carry
vorticity; however, 2D vortex rings and 3D vortex tori are subject to strong
splitting instability. Therefore, it is natural to categorize the basic results
according to physically relevant settings which make it possible to maintain
stability of fundamental (non-topological) and vortex solitons against the
collapse and splitting, respectively. The present review is focused on schemes
that were recently elaborated in terms of Bose-Einstein condensates and similar
photonic setups. These are two-component systems with spin-orbit coupling, and
ones stabilized by the beyond-mean-field Lee-Huang-Yang effect. The latter
setting has been implemented experimentally, giving rise to stable self-trapped
quasi-2D and 3D "quantum droplets".
We report a comprehensive study of magnetotransport properties,
angle-resolved photoemission spectroscopy (ARPES), and density functional
theory (DFT) calculations on self-flux grown LaAuSb$_2$ single crystals.
Resistivity and Hall measurements reveal a charge density wave (CDW) transition
at 77 K. MR and de Haas-Van Alphen (dHvA) measurements indicate that the
transport properties of LaAuSb$_2$ are dominated by Dirac fermions that arise
from Sb square nets. ARPES measurements and DFT calculations reveal an
electronic structure with a common feature of the square-net-based topological
semimetals, which is in good agreement with the magnetotransport properties.
Our results indicate the coexistence of CDW and Dirac fermion in LaAuSb$_2$,
both of which are linked to the bands arising from the Sb-square net,
suggesting that the square net could serve as a structural motif to explore
various electronic orders.
Symmetry Topological Field Theory (SymTFT) is a framework to capture
universal features of quantum many-body systems by viewing them as a boundary
of topological order in one higher dimension. This yielded numerous insights in
static low-energy settings. Here we study what SymTFT can tell about
nonequilibrium, focusing on one-dimensional (1D) driven systems and their 2D
SymTFT. In driven settings, boundary conditions (BCs) can be dynamical and can
apply both spatially and temporally. We show how this enters SymTFT via
topological operators, which we then use to uncover several new results for 1D
dynamics. These include revealing time crystals (TCs) as systems with
symmetry-twisted temporal BCs, finding robust bulk TC features in phases
thought to be only boundary TCs, Floquet dualities, or identifying Floquet
codes as space-time duals to systems with duality-twisted spatial BCs. We also
show how, by making duality-twisted BCs dynamical, non-Abelian braiding of
duality defects can enter SymTFT, leading to effects such as the exact pumping
of symmetry charges between a system and its BCs. We illustrate our ideas for
$\mathbb{Z}_2$-symmetric 1D systems, but our construction applies for any
finite Abelian symmetry.
The fractional quantum Hall (FQH) states are exotic quantum many-body phases
whose elementary charged excitations are neither bosons nor fermions but
anyons, obeying fractional braiding statistics. While most FQH states are
believed to have Abelian anyons, the Moore-Read type states with even
denominators, appearing at half filling of a Landau level (LL), are predicted
to possess non-Abelian excitations with appealing potentials in topological
quantum computation. These states, however, depend sensitively on the orbital
contents of the single-particle LL wavefunction and the mixing between
different LLs. Although they have been observed in a few materials, their
non-Abelian statistics still awaits experimental confirmation. Here we show
magnetotransport measurements on Bernal-stacked trilayer graphene (TLG), whose
unique multiband structure facilitates the interlaced LL mixing, which can be
controlled by external magnetic and displacement fields. We observe a series of
robust FQH states including even-denominator ones at filling factors
$\nu=-9/2$, $-3/2$, $3/2$ and $9/2$. In addition, we are able to finetune the
LL mixing and crossings to drive quantum phase transitions of these
half-filling states and their neighboring odd-denominator ones, exhibiting a
related emerging and waning behavior. Our results establish TLG as a
controllable system for tuning the weights of LL orbitals and mixing strength,
and a fresh platform to seek for non-Abelian quasi-particles.
We report an extensive extensive study of the noncentrosymmetric half-Heusler
topological superconductor YPtBi, revealing unusual relation between bulk
superconductivity and the appearance of surface superconductivity at
temperatures up to 3 times the bulk transition temperature. Transport
measurements confirmed the low carrier density of the material and its bulk
superconducting transition, which was also observed in ac susceptibility
through mutual inductance (MI) measurements. However, a weak signature of
superconductivity in the MI measurements appeared much above the bulk
transition temperature, which was further observed in scanning tunneling
spectroscopy. Polar Kerr effect measurements suggest that while the bulk
superconductor may exhibit an unusual nodal superconducting state, only the
surface state breaks time reversal symmetry. Complementary tunneling
measurements on LuPtBi are used to establish the observations on YPtBi, while
density-functional theory (DFT) calculations may shed light on the origin of
this unusual surface state.
Fractional statistics is one of the most intriguing features of topological
phases in 2D. In particular, the so-called non-Abelian statistics plays a
crucial role towards realizing universal topological quantum computation.
Recently, the study of topological phases has been extended to 3D and it has
been proposed that loop-like extensive objects can also carry fractional
statistics. In this work, we systematically study the so-called three-loop
braiding statistics for loop-like excitations for 3D fermionic topological
phases. Most surprisingly, we discovered new types of non-Abelian three-loop
braiding statistics that can only be realized in fermionic systems (or
equivalently bosonic systems with fermionic particles). The simplest example of
such non-Abelian braiding statistics can be realized in interacting fermionic
systems with a gauge group $\mathbb{Z}_2 \times \mathbb{Z}_8$ or $\mathbb{Z}_4
\times \mathbb{Z}_4$, and the physical origin of non-Abelian statistics can be
viewed as attaching an open Majorana chain onto a pair of linked loops, which
will naturally reduce to the well known Ising non-Abelian statistics via the
standard dimension reduction scheme. Moreover, due to the correspondence
between gauge theories with fermionic particles and classifying fermionic
symmetry-protected topological (FSPT) phases with unitary symmetries, our study
also give rise to an alternative way to classify FSPT phases with unitary
symmetries. We further compare the classification results for FSPT phases with
arbitrary Abelian total symmetry $G^f$ and find systematical agreement with
previous studies using other methods. We believe that the proposed framework of
understanding three-loop braiding statistics (including both Abelian and
non-Abelian cases) in interacting fermion systems applies for generic fermonic
topological phases in 3D.
In recent years, fermionic topological phases of quantum matter has attracted
a lot of attention. In a pioneer work by Gu, Wang and Wen, the concept of
equivalence classes of fermionic local unitary(FLU) transformations was
proposed to systematically understand non-chiral topological phases in 2D
fermion systems and an incomplete classification was obtained. On the other
hand, the physical picture of fermion condensation and its corresponding super
pivotal categories give rise to a generic mathematical framework to describe
fermionic topological phases of quantum matter. In particular, it has been
pointed out that in certain fermionic topological phases, there exists the
so-called q-type anyon excitations, which have no analogues in bosonic
theories. In this paper, we generalize the Gu, Wang and Wen construction to
include those fermionic topological phases with q-type anyon excitations. We
argue that all non-chiral fermionic topological phases in 2+1D are
characterized by a set of tensors
$(N^{ij}_{k},F^{ij}_{k},F^{ijm,\alpha\beta}_{kln,\chi\delta},n_{i},d_{i})$,
which satisfy a set of nonlinear algebraic equations parameterized by phase
factors $\Xi^{ijm,\alpha\beta}_{kl}$, $\Xi^{ij}_{kln,\chi\delta}$,
$\Omega^{kim,\alpha\beta}_{jl}$ and $\Omega^{ki}_{jln,\chi\delta}$. Moreover,
consistency conditions among algebraic equations give rise to additional
constraints on these phase factors which allow us to construct a topological
invariant partition for an arbitrary triangulation of 3D spin manifold.
Finally, several examples with q-type anyon excitations are discussed,
including the Fermionic topological phase from Tambara-Yamagami category for
$\mathbb{Z}_{2N}$, which can be regarded as the $\mathbb{Z}_{2N}$ parafermion
generalization of Ising fermionic topological phase.
Transition metal dichalcogenides layered nano-crystals are emerging as
promising candidates for next-generation optoelectronic and quantum devices. In
such systems, the interaction between excitonic states and atomic vibrations is
crucial for many fundamental properties, such as carrier mobilities, quantum
coherence loss, and heat dissipation. In particular, to fully exploit their
valley-selective excitations, one has to understand the many-body exciton
physics of zone-edge states. So far, theoretical and experimental studies have
mainly focused on the exciton-phonon dynamics in high-energy direct excitons
involving zone-center phonons. Here, we use ultrafast electron diffraction and
ab initio calculations to investigate the many-body structural dynamics
following nearly-resonant excitation of low-energy indirect excitons in MoS2.
By exploiting the large momentum carried by scattered electrons, we identify
the excitation of in-plane K- and Q-phonon modes with E^' symmetry as key for
the stabilization of indirect excitons generated via near-infrared light at
1.55 eV, and we shed light on the role of phonon anharmonicity and the ensuing
structural evolution of the MoS2 crystal lattice. Our results highlight the
strong selectivity of phononic excitations directly associated with the
specific indirect-exciton nature of the wavelength-dependent electronic
transitions triggered in the system.
A striking feature of non-Hermitian systems is the presence of two different
types of topology. One generalizes Hermitian topological phases, and the other
is intrinsic to non-Hermitian systems, which are called line-gap topology and
point-gap topology, respectively. Whereas the bulk-boundary correspondence is a
fundamental principle in the former topology, its role in the latter has not
been clear yet. This paper establishes the bulk-boundary correspondence in the
point-gap topology in non-Hermitian systems. After revealing the requirement
for point-gap topology in the open boundary conditions, we clarify that the
bulk point-gap topology in open boundary conditions can be different from that
in periodic boundary conditions. We give a complete classification of the open
boundary point-gap topology with symmetry and show that the non-trivial open
boundary topology results in robust and exotic surface states.
Stochastic processes are commonly used models to describe dynamics of a wide
variety of nonequilibrium phenomena ranging from electrical transport to
biological motion. The transition matrix describing a stochastic process can be
regarded as a non-Hermitian Hamiltonian. Unlike general non-Hermitian systems,
the conservation of probability imposes additional constraints on the
transition matrix, which can induce unique topological phenomena. Here, we
reveal the role of topology in relaxation phenomena of classical stochastic
processes. Specifically, we define a winding number that is related to topology
of stochastic processes and show that it predicts the existence of a spectral
gap that characterizes the relaxation time. Then, we numerically confirm that
the winding number corresponds to the system-size dependence of the relaxation
time and the characteristic transient behavior. One can experimentally realize
such topological phenomena in magnetotactic bacteria and cell adhesions.
It is well known that two-dimensional (2D) bosons in homogeneous space cannot
undergo real Bose-Einstein condensation, and the superfluid to normal phase
transition is Berezinskii-Kosterlitz-Thouless (BKT) type, associated with
vortex-antivortex pair unbinding. Here we point out a 2D bosonic system whose
low energy physics goes beyond conventional paradigm of 2D {\it homogeneous}
bosons, i.e., intralayer excitons in monolayer transition metal
dichalcogenides. With intrinsic valley-orbit coupling and valley Zeeman energy,
exciton dispersion becomes linear at small momentum, giving rise to a series of
novel features. The critical temperature of Bose-Einstein condensation of these
excitons is nonzero, suggesting true long-range order in 2D homogeneous system.
The dispersion of Goldstone mode at long wavelength has the form
$\varepsilon(\boldsymbol{q})\sim\sqrt{q}$, in contrast to conventional linear
phonon spectrum. The vortex energy deviates from the usual logarithmic form
with respect to system size, but instead has an additional linear term.
Superfluid to normal phase transition is no longer BKT type for system size
beyond a characteristic scale, without discontinuous jump in superfluid
density. With the recent experimental progress on exciton fluid at thermal
equilibrium in monolayer semiconductors, our work points out an experimentally
accessible system to search for unconventional 2D superfluids beyond BKT
paradigm.
Motivated by scanning tunneling microscopy experiments on $A$V$_3$Sb$_5$ ($A$
= Cs, Rb, K) that revealed periodic real-space modulation of electronic states
at low energies, I show using model calculations that a triple-{\bf Q} chiral
pair density wave (CPDW) is generated in the superconducting state by a charge
order of $2a\! \times \!2a$ superlattice periodicity, intertwined with a
time-reversal symmetry breaking orbital loop current. In the presence of such a
charge order and orbital loop current, the superconducting critical field is
enhanced beyond the Chandrasekhar-Clogston limit. The CPDW correlation survives
even when the long-range superconducting phase coherence is diminished by a
magnetic field or temperature, stabilizing an exotic granular superconducting
state above and in the vicinity of the superconducting transition. The
presented results suggest that the CPDW can be regarded as the origin of the
pseudogap observed near the superconducting transition.
The interface composed of magnets and strong spin-orbit coupling (SOC)
materials forms an important platform for spintronic devices and intriguing
magnetic phenomena, such as the chiral spin textures and magnetic proximity
effect (MPE). The interface exchange interaction and Dzyaloshinskii-Moriya
interaction (DMI) have been discussed in a wide range of heterostructures,
while the crystal stacking geometry modulation on these interface interactions
has rarely been considered. Here, we show a pronounced geometry modulation on
the interface magnetism through comparing a rutile and an anatase IrO2 capping
on a ferrimagnetic CoFe2O4. The rutile heterostructure with a high-symmetry
interface shows a conventional anomalous Hall effect (AHE) profile due to the
MPE. In contrast, the anatase one with a low-symmetry interface exhibits a
topological-like AHE even at zero-field, suggesting the emergence of
non-coplanar magnetic order at the interface. Our results suggest that the
influence of DMI at the interface can be more accentuated by forming a
low-symmetry interface and raises a new means of designing interface magnetism
via the geometry modulation.
We introduce a Brownian $p$-state clock model in two dimensions and
investigate the nature of phase transitions numerically. As a nonequilibrium
extension of the equilibrium lattice model, the Brownian $p$-state clock model
allows spins to diffuse randomly in the two-dimensional space of area $L^2$
under periodic boundary conditions. We find three distinct phases for $p>4$: a
disordered paramagnetic phase, a quasi-long-range-ordered critical phase, and
an ordered ferromagnetic phase. In the intermediate critical phase, the
magnetization order parameter follows a power law scaling $m \sim
L^{-\tilde{\beta}}$, where the finite-size scaling exponent $\tilde{\beta}$
varies continuously. These critical behaviors are reminiscent of the double
Berezinskii-Kosterlitz-Thouless~(BKT) transition picture of the equilibrium
system. At the transition to the disordered phase, the exponent takes the
universal value $\tilde\beta = 1/8$ which coincides with that of the
equilibrium system. This result indicates that the BKT transition driven by the
unbinding of topological excitations is robust against the particle diffusion.
On the contrary, the exponent at the symmetry-breaking transition to the
ordered phase deviates from the universal value $\tilde{\beta} = 2/p^2$ of the
equilibrium system. The deviation is attributed to a nonequilibrium effect from
the particle diffusion.
We present a first-principles study of the low-temperature rhombohedral phase
of BaTiO$_3$ using Hubbard-corrected density-functional theory. By employing
density-functional perturbation theory, we compute the onsite Hubbard $U$ for
Ti($3d$) states and the intersite Hubbard $V$ between Ti($3d$) and O($2p$)
states. We show that applying the onsite Hubbard $U$ correction alone to
Ti($3d$) states proves detrimental, as it suppresses the Ti($3d$)-O($2p$)
hybridization and drives the system towards a cubic phase. Conversely, when
both onsite $U$ and intersite $V$ are considered, the localized character of
the Ti($3d$) states is maintained, while also preserving the Ti($3d$)-O($2p$)
hybridization, restoring the rhombohedral phase of BaTiO$_3$. The generalized
PBEsol+$U$+$V$ functional yields good agreement with experimental results for
the band gap and dielectric constant, while the optimized geometry is slightly
less accurate compared to PBEsol. Zone-center phonon frequencies and Raman
spectra are found to be significantly influenced by the underlying geometry.
PBEsol and PBEsol+$U$+$V$ provide satisfactory agreement with the experimental
Raman spectrum when the PBEsol geometry is used, while PBEsol+$U$ Raman
spectrum diverges strongly from experimental data highlighting the adverse
impact of the $U$ correction alone in BaTiO$_3$. Our findings underscore the
promise of the extended Hubbard PBEsol+$U$+$V$ functional with first-principles
$U$ and $V$ for the investigation of other ferroelectric perovskites with mixed
ionic-covalent interactions.
We study the influence of quantizing perpendicular magnetic fields on the
ground state of a bilayer with electron and hole fluids separated by an opaque
tunnel barrier. In the absence of a field, the ground state at low carrier
densities is a condensate of s-wave excitons that has spontaneous interlayer
phase coherence. We find that a series of phase transitions emerge at strong
perpendicular fields between condensed states and incompressible incoherent
states with full electron and hole Landau levels. When the electron and hole
densities are unequal, condensation can occur in higher angular momentum
electron-hole pair states and, at weak fields, break rotational symmetry. We
explain how this physics is expressed in dual-gate phase diagrams, and predict
transport and capacitively-probed thermodynamic signatures that distinguish
different states.
The fractional quantum anomalous Hall effect (FQAHE), the analog of the
fractional quantum Hall effect1 at zero magnetic field, is predicted to exist
in topological flat bands under spontaneous time-reversal-symmetry breaking.
The demonstration of FQAHE could lead to non-Abelian anyons which form the
basis of topological quantum computation. So far, FQAHE has been observed only
in twisted MoTe2 (t-MoTe2) at moire filling factor v > 1/2. Graphene-based
moire superlattices are believed to host FQAHE with the potential advantage of
superior material quality and higher electron mobility. Here we report the
observation of integer and fractional QAH effects in a rhombohedral pentalayer
graphene/hBN moire superlattice. At zero magnetic field, we observed plateaus
of quantized Hall resistance Rxy = h/(ve^2) at filling factors v = 1, 2/3, 3/5,
4/7, 4/9, 3/7 and 2/5 of the moire superlattice respectively. These features
are accompanied by clear dips in the longitudinal resistance Rxx. In addition,
at zero magnetic field, Rxy equals 2h/e^2 at v = 1/2 and varies linearly with
the filling factor-similar to the composite Fermi liquid (CFL) in the
half-filled lowest Landau level at high magnetic fields. By tuning the gate
displacement field D and v, we observed phase transitions from CFL and FQAH
states to other correlated electron states. Our graphene system provides an
ideal platform for exploring charge fractionalization and (non-Abelian) anyonic
braiding at zero magnetic field, especially considering a lateral junction
between FQAHE and superconducting regions in the same device.
We study the morphology of the Saturn ring defect and director structure
around a colloidal particle with normal anchoring conditions and within the
flow of the nematic host phase through a rectangular duct of comparable size to
the particle. The changes in the defect structures and director profile
influence the advection behaviour of the particle, which we compare to that in
a simple Newtonian host phase. These effects lead to a non-monotonous
dependence of the differential velocity of particle and fluid, also known as
retardation ratio, on the Ericksen number.
Transition-metal honeycomb compounds are capturing scientific attention due
to their distinctive electronic configurations, underscored by the
triangular-lattice spin-orbit coupling and competition between multiple
interactions, paving the way for potential manifestations of phenomena such as
Dirac semimetal, superconductivity, and quantum spin liquid states. These
compounds can undergo discernible pressure-induced alterations in their
crystallographic and electronic paradigms, as exemplified by our high-pressure
(HP) synthesis and exploration of the honeycomb polymorph of ReO3 (P6322). This
HP-P6322 polymorph bears a phase transition from P6322 to P63/mmc upon cooling
around Tp = 250 K, as evidenced by the evolution of temperature-dependent
magnetization (M-T curves), cell dimension, and conductivity initiated by an
inherent bifurcation of the oxygen position in the ab plane. Insightful
analysis of its band structure positions suggests this HP-P6322 polymorph being
a plausible candidate for Dirac semimetal properties. This phase transition
evokes anomalies in the temperature-dependent variation of paramagnetism
(non-linearity) and a crossover from semiconductor to temperature-independent
metal, showing a temperature independent conductivity behavior below ~200 K.
Under increasing external pressure, both the Tp and resistance of this
HP-polymorph is slightly magnetic-field dependent and undergo a "V"-style
evolution (decreasing and then increasing) before becoming pressure independent
up to 20.2 GPa. Theoretical calculations pinpoint this anionic disorder as a
probable catalyst for the decrement in the conductive efficiency and muted
temperature-dependent conductivity response.
The Schwinger model, one-dimensional quantum electrodynamics, has CP symmetry
at $\theta = \pi$ due to the topological nature of the $\theta$ term. At zero
temperature, it is known that as increasing the fermion mass, the system
undergoes a second-order phase transition to the CP broken phase, which belongs
to the same universality class as the quantum Ising chain. In this paper, we
obtain the phase diagram near the quantum critical point (QCP) in the
temperature and fermion mass plane using first-principle Monte Carlo
simulations, while avoiding the sign problem by using the lattice formulation
of the bosonized Schwinger model. Specifically, we perform a detailed
investigation of the correlation function of the electric field near the QCP
and find that its asymptotic behavior can be described by the universal scaling
function of the quantum Ising chain. This finding indicates the existence of
three regions near the QCP, each characterized by a specific asymptotic form of
the correlation length, and demonstrates that the CP symmetry is restored at
any nonzero temperature, entirely analogous to the quantum Ising chain. The
range of the scaling behavior is also examined and found to be particularly
wide.
Landau levels perturbed by a periodic potential is a prime setting to design
quantum systems with exotic fractal spectra. Motivated by recent advances in
twistronics, we introduce `Hofstadter quasicrystal' problem describing Landau
levels perturbed by a set of incommensurate cosine waves. We illustrate the
underlying physics for moir\'{e} quasicrystals with octagonal and dodecagonal
symmetries, finding spectra that are vastly more complex than the Hofstadter
spectrum. Surprisingly, due to the high spatial symmetry, the quasicrystal
problem exhibits hidden `inner' symmetry arising at special `magic' values of
the magnetic field. The $1/B$-periodic pattern of magic field values explains
striking wide-range oscillations in the observed spectra that have irrational
periodicity incommensurate with the Aharonov-Bohm and Brown-Zak periodicities.
The prominent character of these oscillations makes them readily accessible in
state-of-the-art moir\'{e} graphene systems.
A microscopic control over the origin and dynamics of localised spin centres
in lower dimensional solids turns out to be a key factor for next generation
spintronics and quantum technologies. With the help of low temperature electron
paramagnetic resonance (EPR) measurements, supported by the first-principles
calculations within density functional theory (DFT) formulation, we found the
origin of different high-spin paramagnetic intrinsic charge-centres, Mo3+(4d3)
and Mo2+(4d4) present in the nano-crystalline sulfur deficit hexagonal
molybdenum disulfide (2H-MoS_(2-x)), against the established notion of spin-1/2
, Mo5+ centres. A critical strain generated in the nano-structured 2H-MoS_(2-x)
was found to be very crucial for spin-localization in this layered material.
Indeed, computationally effective proposition of the PBE+U
exchange-correlations within DFT including D3-dispersion corrections found to
be more viable than expensive higher rung of exchange-correlation functionals,
explored earlier. It is also found that the oxygen vacancy of the reduced oxide
phase, embedded in 2H-MoS_(2-x) host lattice, has the longest relaxation times.
Moreover, the temperature dependence of spin-lattice relaxation measurements
reveals a direct process for interstitial spin centres and a Raman process for
both sulfur and oxygen vacancy sites. We expect such observation would be a
valuable pillar for better understanding of the next generation quantum
technologies and device applications.
Transport experiments in twisted bilayer graphene (TBG) show a fan-like
region near integer fillings with a resistivity linear in temperature down to
the lowest temperature measured. This suggests quantum-critical points at the
boundaries to long-range ordered phases. The particular order proposed by
Blutinck et al. for twisted bi-layer graphene (TBG) is a loop-current order at
the carbon length-scale together with modulations on the moir\'e length scale.
This is shown to be the ground state of a xy model with translational symmetry
and time-reversal broken. Here, this is extended to derive a model for
quantum-critical properties. We derive the quantum xy model coupled to fermions
in this situation. The kinetic energy operator for the model and the coupling
of fermions to the fluctuations of the xy model are derived. The previously
derived universal properties in the quantum-critical region of such a model,
leading to a marginal Fermi-liquid, irrespective of the underlying microscopics
is briefly reviewed. The properties include the resistivity and various other
transport properties with and without applying a magnetic field and the
instability of the quantum fluctuating state to superconductivity in d-wave
symmetry.

Date of feed: Fri, 29 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) **Exploration of field-like torque and field-angle tunability in coupled spin-torque nano oscillators for synchronization. (arXiv:2312.16175v1 [cond-mat.mes-hall])**

R. Arun, R. Gopal, V. K. Chandrasekar, M. Lakshmanan

**Purity-dependent Lorenz number, electron hydrodynamics and electron-phonon coupling in WTe$_2$. (arXiv:2312.16178v1 [cond-mat.mes-hall])**

Wei Xie, Feng Yang, Liangcai Xu, Xiaokang Li, Zengwei Zhu, Kamran Behnia

**Nonequilibrium formulation of varying-temperature bit erasure. (arXiv:2312.16195v1 [cond-mat.stat-mech])**

Stephen Whitelam

**Massive Klein Tunneling in Topological Photonic Crystals. (arXiv:2312.16207v1 [cond-mat.mes-hall])**

Keiji Nakatsugawa, Xiao Hu

**Non-Invertible Anyon Condensation and Level-Rank Dualities. (arXiv:2312.16317v1 [hep-th])**

Clay Cordova, Diego García-Sepúlveda

**Achieving 100% amplitude modulation depth in a graphene-based tuneable capacitance metamaterial. (arXiv:2312.16330v1 [physics.optics])**

Ruqiao Xia, Nikita W. Almond, Stephen J. Kindness, Sergey A. Mikhailov, Wadood Tadbier, Riccardo Degl'Innocenti, Yuezhen Lu, Abbie Lowe, Ben Ramsay, Lukas A. Jakob, James Dann, Stephan Hofmann, Harvey E. Beere, David A. Ritchie, Wladislaw Michailow

**Convergence of Ginzburg-Landau expansions: superconductivity in the BCS theory and chiral symmetry breaking in the NJL model. (arXiv:2312.16372v1 [hep-th])**

William Gyory, Naoki Yamamoto

**Structural stability, electronic band structure, and optoelectronic properties of quaternary chalcogenide CuZn2MS4 (M =In and Ga) compounds via first principles. (arXiv:2312.16390v1 [cond-mat.mtrl-sci])**

Anima Ghosh, R.Thangavel

**Optical probe on doping modulation of magnetic Weyl semimetal Co3Sn2S2. (arXiv:2312.16437v1 [cond-mat.mes-hall])**

L. Wang (1), S. Zhang (2), B. B. Wang (2), B. X. Gao (1), L. Y. Cao (1), X. T. Zhang (1), X. Y. Zhang (1), E. K. Liu (2), R. Y. Chen (1) ((1) Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing China (2) State Key Laboratory for Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing China)

**Dynamics of a Nonequilibrium Discontinuous Quantum Phase Transition in a Spinor Bose-Einstein Condensate. (arXiv:2312.16555v1 [cond-mat.quant-gas])**

Matthew T. Wheeler, Hayder Salman, Magnus O. Borgh

**Fractional-statistics-induced entanglement from Andreev-like tunneling. (arXiv:2312.16556v1 [cond-mat.mes-hall])**

Gu Zhang, Pierre Glidic, Frederic Pierre, Igor Gornyi, Yuval Gefen

**tda-segmentor: A tool to extract and analyze local structure and porosity features in porous materials. (arXiv:2312.16558v1 [cond-mat.mtrl-sci])**

Aditya Vasudevan, Jorge Zorrilla Prieto, Sergei Zorkaltsev, Maciej Haranczyk

**Disorder driven Thouless charge pump in a quasiperiodic chain. (arXiv:2312.16568v1 [cond-mat.quant-gas])**

Ashirbad Padhan, Tapan Mishra

**Combined effect of SiC and carbon on sintering kinetics, microstructure and mechanical properties of fine-grained binderless tungsten carbide. (arXiv:2312.16579v1 [cond-mat.mtrl-sci])**

E.A. Lantsev (1), P.V. Andreev (1), A.V. Nokhrin (1), Yu.V. Blagoveshchenskiy (2), N.V. Isaeva (2,3), M.S. Boldin (1), A.A. Murashov (1), G.V. Shcherbak (1), K.E. Smetanina (1), V.N. Chuvil'deev (1), N.Yu. Tabachkova (3, 4) ((1) Lobachevsky State University of Nizhny Novgorod, (2) A.A. Baykov Institute of Metallurgy and Materials Science of the Russian Academy of Sciences, (3) National University of Science and Technology "MISIS", (4) A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences)

**Topological phase transitions induced by the variation of exchange couplings in graphene. (arXiv:2312.16625v1 [cond-mat.mes-hall])**

Jihyeon Park, Gun Sang Jeon

**Passive defect driven morphogenesis in nematic membranes. (arXiv:2312.16654v1 [cond-mat.soft])**

D. J. G. Pearce, C. Thibault, Q. Chaboche, C. Blanch-Mercader

**Square Moir\'e Superlattices in Twisted Two-Dimensional Halide Perovskites. (arXiv:2312.16679v1 [cond-mat.mtrl-sci])**

Shuchen Zhang, Linrui Jin, Yuan Lu, Linghai Zhang, Jiaqi Yang, Qiuchen Zhao, Dewei Sun, Joshua J. P. Thompson, Biao Yuan, Ke Ma, Akriti, Jee Yung Park, Yoon Ho Lee, Zitang Wei, Blake P. Finkenauer, Daria D. Blach, Sarath Kumar, Hailin Peng, Arun Mannodi-Kanakkithodi, Yi Yu, Ermin Malic, Gang Lu, Letian Dou, Libai Huang

**Topological Phase Transitions in the Disordered Haldane Model. (arXiv:2312.16689v1 [cond-mat.str-el])**

J. Mildner, M. D. Caio, G. Möller, N. R. Cooper, M. J. Bhaseen

**CdTe and HgTe doped with V, Cr, and Mn -- prospects for the quantum anomalous Hall effect. (arXiv:2312.16732v1 [cond-mat.mtrl-sci])**

Giuseppe Cuono, Carmine Autieri, Tomasz Dietl

**Correlated Quantum Phenomena of Spin-Orbit Coupled Perovskite Oxide Heterostructures: Cases of SrRuO3 and SrIrO3-Based Artificial Superlattices. (arXiv:2312.16748v1 [cond-mat.str-el])**

Seung Gyo Jeong, Jin Young Oh, Lin Hao, Jian Liu, Woo Seok Choi

**Memristive behavior of functionalized graphene quantum dot and polyaniline nanocomposites. (arXiv:2312.16759v1 [cond-mat.mes-hall])**

Debi Prasad Pattnaik, Abu Bakar Siddique, Alex T. Bregazzi, Pavel Borisov, Mallar Ray, Sergey Savel'ev, Niladri Banerjee

**Collective spin oscillations in a magnetized graphene sheet. (arXiv:2312.16782v1 [cond-mat.mes-hall])**

M. Agarwal, O. A. Starykh, D. A. Pesin, E. G. Mishchenko

**Influence of Dynamical Floquet Spectrum on the Plasmon Excitations and Exchange Energy of tilted monolayer 1T$^\prime$MoS$_2$. (arXiv:2312.16825v1 [cond-mat.mes-hall])**

Sita Kandel, Godfrey Gumbs, Antonios Balassis, Andrii Iurov, Oleksiy Roslyak

**Defect bound states in the continuum without symmetry protection: bilayer graphene and beyond. (arXiv:2312.16844v1 [cond-mat.mes-hall])**

Daniel Massatt, Stephen P. Shipman, Ilya Vekhter, Justin H. Wilson

**A novel two-dimensional all-carbon Dirac node-line semimetal. (arXiv:2312.16853v1 [cond-mat.mtrl-sci])**

Youjie Wang, Qian Gao, Zhenpeng Hu

**Orientational order and topological defects in a dilute solutions of rodlike polymers at low Reynolds number. (arXiv:2312.16873v1 [physics.flu-dyn])**

Leonardo Puggioni, Stefano Musacchio

**Higgs-Confinement Transitions in QCD from Symmetry Protected Topological Phases. (arXiv:2312.16898v1 [hep-th])**

Thomas T. Dumitrescu, Po-Shen Hsin

**Detecting bulk carbon ferromagnetism in graphene multi-edge structure. (arXiv:2312.16925v1 [cond-mat.mtrl-sci])**

Chao Wang, Nan Jian, Meijie Yin, Xi Zhang, Zhi Yang, Xiuhao Mo, Takashi Kikkawa, Shunsuke Daimon, Eiji Saitoh, Qian Li, Wensheng Yan, Dazhi Hou, Lei Yang, Dongfeng Diao

**Solitons in binary compounds with stacked two-dimensional honeycomb lattices. (arXiv:2312.16949v1 [cond-mat.mes-hall])**

James H. Muten, Louise H. Frankland, Edward McCann

**Topological Edge and Corner States in Biphenylene Photonic Crystal. (arXiv:2312.16952v1 [physics.optics])**

Huyen Thanh Phan, Keiki Koizumi, Feng Liu, Katsunori Wakabayashi

**Quantum Weyl-Heisenberg antiferromagnet. (arXiv:2312.17028v1 [cond-mat.str-el])**

Peter Rosenberg, Efstratios Manousakis

**Superconductivity in nickelate and cuprate superconductors with strong bilayer coupling. (arXiv:2312.17064v1 [cond-mat.supr-con])**

Zhen Fan, Jian-Feng Zhang, Bo Zhan, Dingshun Lv, Xing-Yu Jiang, Bruce Normand, Tao Xiang

**A new double-layered kagome antiferromagnet ScFe$_6$Ge$_4$. (arXiv:2312.17069v1 [cond-mat.str-el])**

M. A. Kassem, T. Shiotani, H. Ohta, Y. Tabata, T. Waki, H. Nakamura

**Magneto-Crystalline Composite Topological Defects and Half-Hopfions. (arXiv:2312.17083v1 [cond-mat.mes-hall])**

Sahal Kaushik, Filipp N. Rybakov, Egor Babaev

**Multidimensional Soliton Systems. (arXiv:2312.17096v1 [nlin.PS])**

Boris A. Malomed

**Coexistence of Dirac fermion and charge density wave in square-net-based semimetal LaAuSb2. (arXiv:2312.17143v1 [cond-mat.mtrl-sci])**

Xueliang Wu, Zhixiang Hu, David Graf, Yu Liu, Chaoyue Deng, Huixia Fu, Asish K. Kundu, Tonica Valla, Cedomir Petrovic, Aifeng Wang

**SymTFT out of equilibrium: from time crystals to braided drives and Floquet codes. (arXiv:2312.17176v1 [cond-mat.str-el])**

Vedant Motamarri, Campbell McLauchlan, Benjamin Béri

**Tunable even- and odd-denominator fractional quantum Hall states in trilayer graphene. (arXiv:2312.17204v1 [cond-mat.mes-hall])**

Yiwei Chen, Yan Huang, Qingxin Li, Bingbing Tong, Guangli Kuang, Chuanying Xi, Kenji Watanabe, Takashi Taniguchi, Guangtong Liu, Zheng Zhu, Li Lu, Fu-Chun Zhang, Ying-Hai Wu, Lei Wang

**Possible Unconventional Surface Superconductivity in the Half-Heusler YPtBi. (arXiv:2312.17213v1 [cond-mat.supr-con])**

Eylon Persky, Alan Fang, Xinyang Zhang, Carolina Adamo, Eli Levenson-Falk, Chandra Shekhar, Claudia Felser, Binghai Yan, Aharon Kapitulnik

**Non-Abelian Three-Loop Braiding Statistics for 3D Fermionic Topological Phases. (arXiv:1912.13505v2 [cond-mat.str-el] UPDATED)**

Jing-Ren Zhou, Qing-Rui Wang, Chenjie Wang, Zheng-Cheng Gu

**Towards a complete classification of non-chiral topological phases in 2D fermion systems. (arXiv:2112.06124v2 [cond-mat.str-el] UPDATED)**

Jing-Ren Zhou, Qing-Rui Wang, Zheng-Cheng Gu

**Indirect exciton-phonon dynamics in MoS2 revealed by ultrafast electron diffraction. (arXiv:2112.15240v2 [cond-mat.mes-hall] UPDATED)**

Jianbo Hu, Yang Xiang, Beatrice Matilde Ferrari, Emilio Scalise, Giovanni Maria Vanacore

**Bulk-boundary correspondence in point-gap topological phases. (arXiv:2205.15635v3 [cond-mat.mes-hall] UPDATED)**

Daichi Nakamura, Takumi Bessho, Masatoshi Sato

**Role of Topology in Relaxation of One-Dimensional Stochastic Processes. (arXiv:2301.09832v3 [cond-mat.stat-mech] UPDATED)**

Taro Sawada, Kazuki Sone, Ryusuke Hamazaki, Yuto Ashida, Takahiro Sagawa

**Searching for Unconventional Superfluid in Excitons of Monolayer Semiconductors. (arXiv:2302.05585v2 [cond-mat.quant-gas] UPDATED)**

Wei Chen, Chun-Jiong Huang, Qizhong Zhu

**Chiral pair density wave as a precursor of the pseudogap in kagom\'e superconductors. (arXiv:2306.06242v2 [cond-mat.supr-con] UPDATED)**

Narayan Mohanta

**Signature of geometry modulation on interface magnetism emerged in isomeric IrO2-CoFe2O4 heterostructures. (arXiv:2307.07169v2 [cond-mat.mtrl-sci] UPDATED)**

Meng Wang, Shunsuke Mori, Xiuzhen Yu, Masahiro Sawada, Naoya Kanazawa, Pu Yu, Fumitaka Kagawa

**Nonequilibrium phase transitions in a Brownian $p$-state clock model. (arXiv:2307.09945v2 [cond-mat.stat-mech] UPDATED)**

Chul-Ung Woo, Jae Dong Noh

**Understanding the role of Hubbard corrections in the rhombohedral phase of BaTiO$_3$. (arXiv:2309.04348v2 [cond-mat.mtrl-sci] UPDATED)**

G. Gebreyesus, Lorenzo Bastonero, Michele Kotiuga, Nicola Marzari, Iurii Timrov

**Electrical Control of Two-Dimensional Electron-Hole Fluids in the Quantum Hall Regime. (arXiv:2309.04600v2 [cond-mat.mes-hall] UPDATED)**

Bo Zou, Yongxin Zeng, A.H. MacDonald, Artem Strashko

**Fractional Quantum Anomalous Hall Effect in a Graphene Moire Superlattice. (arXiv:2309.17436v4 [cond-mat.mes-hall] UPDATED)**

Zhengguang Lu, Tonghang Han, Yuxuan Yao, Aidan P. Reddy, Jixiang Yang, Junseok Seo, Kenji Watanabe, Takashi Taniguchi, Liang Fu, Long Ju

**Defect-influenced particle advection in highly confined liquid crystal flows. (arXiv:2310.18667v2 [cond-mat.soft] UPDATED)**

Magdalena Lesniewska, Nigel Mottram, Oliver Henrich

**Signature of Topological Semimetal in Harmonic-honeycomb ReO3. (arXiv:2310.20341v2 [cond-mat.mtrl-sci] UPDATED)**

Yifeng Han, Cui-Qun Chen, Hualei Sun, Shuang Zhao, Long Jiang, Yuxuan Liu, Zhongxiong Sun, Meng Wang, Hongliang Dong, Ziyou Zhang, Zhiqiang Chen, Bin Chen, Dao-Xin Yao, Man-Rong Li

**Phase diagram near the quantum critical point in Schwinger model at $\theta = \pi$: analogy with quantum Ising chain. (arXiv:2311.04738v2 [hep-lat] UPDATED)**

Hiroki Ohata

**Hofstadter quasicrystals, hidden symmetries and irrational quantum oscillations. (arXiv:2311.16967v2 [cond-mat.mes-hall] UPDATED)**

Kirill Kozlov, Grigor Adamyan, Mariia Kryvoruchko, Yelizaveta Kulynych, Leonid Levitov

**Strain-driven Charge Localisation and Spin Dynamics of Paramagnetic Defects in S-deficit 2H-MoS2 Nanocrystals. (arXiv:2312.12805v2 [cond-mat.mtrl-sci] UPDATED)**

Sudipta Khamrui, Kamini Bharti, Daniella Goldfarb, Tilak Das, Debamalya Banerjee

**Quantum-criticality in twisted bi-layer graphene. (arXiv:2312.15410v2 [cond-mat.str-el] UPDATED)**

C. M. Varma

Found 3 papers in prb Negative magnetoresistance (NMR) is a marked feature of Dirac semimetals, and may be caused by multiple mechanisms, such as the chiral anomaly, the Zeeman energy, the quantum interference effect, and the orbital moment. Recently, an experiment on Dirac semimetal ${\mathrm{Cd}}_{3}{\mathrm{As}}_{2}$ … Recent experiments on $t$MoTe${}_{2}$ provide the first realization of the fractional quantum anomalous Hall effect. Synthesizing insights from an extensive exact diagonalization study, the authors present here a many-body phase diagram $t$MoTe${}_{2}$, in which lowest Landau level (LLL)-like features and non-LLL-like features coexist. The study highlights several guiding principles, including interaction-enhanced particle-hole asymmetry, that is expected to play an important role in general fractional quantum anomalous Hall systems. The quantum anomalous Hall effect (QAHE) is a topological state of matter with a quantized Hall resistance. It has been observed in some two-dimensional insulating materials such as magnetic topological insulator films and twisted bilayer graphene. These materials are insulating in the bulk but poss…

Date of feed: Fri, 29 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) **Van Hove singularity–induced negative magnetoresistance in Dirac semimetals**

Kai-He Ding and Zhen-Gang Zhu

Author(s): Kai-He Ding and Zhen-Gang Zhu

[Phys. Rev. B 108, 245158] Published Thu Dec 28, 2023

**Toward a global phase diagram of the fractional quantum anomalous Hall effect**

Aidan P. Reddy and Liang Fu

Author(s): Aidan P. Reddy and Liang Fu

[Phys. Rev. B 108, 245159] Published Thu Dec 28, 2023

**Metallic quantized anomalous Hall effect without chiral edge states**

Kai-Zhi Bai, Bo Fu, Zhenyu Zhang, and Shun-Qing Shen

Author(s): Kai-Zhi Bai, Bo Fu, Zhenyu Zhang, and Shun-Qing Shen

[Phys. Rev. B 108, L241407] Published Thu Dec 28, 2023

Found 3 papers in prl Spin textures with various topological orders are of great theoretical and practical interest. Hopfion, a spin texture characterized by a three-dimensional topological order was recently realized in electronic spin systems. Here, we show that monochromatic light can be structured such that its photo… The Grüneisen parameter ($γ$) is crucial for determining many thermal properties, including the anharmonic effect, thermostatistics, and equation of state of materials. However, the isentropic adiabatic compression conditions required to measure the Grüneisen parameter under high pressure are diffic… Topological defects in active polar fluids can organize spontaneous flows and influence macroscopic density patterns. Both of them play an important role during animal development. Yet the influence of density on active flows is poorly understood. Motivated by experiments on cell monolayers confined…

Date of feed: Fri, 29 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) **Photonic Spin Hopfions and Monopole Loops**

Haiwen Wang and Shanhui Fan

Author(s): Haiwen Wang and Shanhui Fan

[Phys. Rev. Lett. 131, 263801] Published Thu Dec 28, 2023

**Expanding the Pressure Frontier in Grüneisen Parameter Measurement: Study of Sodium Chloride**

Jun Kong, Kaiyuan Shi, Xingbang Dong, Xiao Dong, Xin Zhang, Jiaqing Zhang, Lei Su, and Guoqiang Yang

Author(s): Jun Kong, Kaiyuan Shi, Xingbang Dong, Xiao Dong, Xin Zhang, Jiaqing Zhang, Lei Su, and Guoqiang Yang

[Phys. Rev. Lett. 131, 266101] Published Thu Dec 28, 2023

**Density-Polarity Coupling in Confined Active Polar Films: Asters, Spirals, and Biphasic Orientational Phases**

Mathieu Dedenon, Claire A. Dessalles, Pau Guillamat, Aurélien Roux, Karsten Kruse, and Carles Blanch-Mercader

Author(s): Mathieu Dedenon, Claire A. Dessalles, Pau Guillamat, Aurélien Roux, Karsten Kruse, and Carles Blanch-Mercader

[Phys. Rev. Lett. 131, 268301] Published Thu Dec 28, 2023

Found 9 papers in nano-lett

Date of feed: Thu, 28 Dec 2023 22:18:02 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) **[ASAP] Tip Growth of Quasi-Metallic Bilayer Graphene Nanoribbons with Armchair Chirality**

Shuo Lou, Bosai Lyu, Jiajun Chen, Xianliang Zhou, Wenwu Jiang, Lu Qiu, Peiyue Shen, Saiqun Ma, Zhichun Zhang, Yufeng Xie, Zhenghan Wu, Yi Chen, Kunqi Xu, Qi Liang, Kenji Watanabe, Takashi Taniguchi, Lede Xian, Guangyu Zhang, Wengen Ouyang, Feng Ding, and Zhiwen ShiNano LettersDOI: 10.1021/acs.nanolett.3c03534

**[ASAP] Anomalous Hall Transport by Optically Injected Isospin Degree of Freedom in Dirac Semimetal Thin Film**

Yuta Murotani, Natsuki Kanda, Tomohiro Fujimoto, Takuya Matsuda, Manik Goyal, Jun Yoshinobu, Yohei Kobayashi, Takashi Oka, Susanne Stemmer, and Ryusuke MatsunagaNano LettersDOI: 10.1021/acs.nanolett.3c03770

**[ASAP] Synchronizing Efficient Purification of VOCs in Durable Solar Water Evaporation over a Highly Stable Cu/W18O49@Graphene Material**

Liteng Ren, Xiaonan Yang, Xin Sun, and Yupeng YuanNano LettersDOI: 10.1021/acs.nanolett.3c04166

**[ASAP] Free-Standing Carbon Nanotube Embroidered Graphene Film Electrode Array for Stable Neural Interfacing**

Lei Gao, Suye Lv, Yuanyuan Shang, Shouliang Guan, Huihui Tian, Ying Fang, Jinfen Wang, and Hongbian LiNano LettersDOI: 10.1021/acs.nanolett.3c03421

**[ASAP] Nanoscale Manipulation of Exciton–Trion Interconversion in a MoSe2 Monolayer via Tip-Enhanced Cavity-Spectroscopy**

Mingu Kang, Su Jin Kim, Huitae Joo, Yeonjeong Koo, Hyeongwoo Lee, Hyun Seok Lee, Yung Doug Suh, and Kyoung-Duck ParkNano LettersDOI: 10.1021/acs.nanolett.3c03920

**[ASAP] Regulating Lewis Acidic Sites of 1T-2H MoS2 Catalysts for Solar-Driven Photothermal Catalytic H2 Production from Lignocellulosic Biomass**

Chi Ma, Miao Cheng, Qing-Yu Liu, Yong-Jun Yuan, Fu-Guang Zhang, Naixu Li, Jie Guan, Zhi-Kai Shen, Zhen-Tao Yu, and Zhigang ZouNano LettersDOI: 10.1021/acs.nanolett.3c03947

**[ASAP] Electroluminescence as a Probe of Strong Exciton–Plasmon Coupling in Few-Layer WSe2**

Yunxuan Zhu, Jiawei Yang, Jaime Abad-Arredondo, Antonio I. Fernández-Domínguez, Francisco J. Garcia-Vidal, and Douglas NatelsonNano LettersDOI: 10.1021/acs.nanolett.3c04684

**[ASAP] High-Performance Photodetectors Based on Semiconducting Graphene Nanoribbons**

Mingyang Wang, Xiaoxiao Zheng, Xiaoling Ye, Wencheng Liu, Baoqing Zhang, Zihao Zhang, Rongli Zhai, Yafei Ning, Hu Li, and Aimin SongNano LettersDOI: 10.1021/acs.nanolett.3c03563

**[ASAP] Nanoparticle Deep-Subwavelength Dynamics Empowered by Optical Meron–Antimeron Topology**

Chengfeng Lu, Bo Wang, Xiang Fang, Din Ping Tsai, Weiming Zhu, Qinghua Song, Xiao Deng, Tao He, Xiaoyun Gong, Hong Luo, Zhanshan Wang, Xinhua Dai, Yuzhi Shi, and Xinbin ChengNano LettersDOI: 10.1021/acs.nanolett.3c03351

Found 7 papers in acs-nano

Date of feed: Thu, 28 Dec 2023 22:22:51 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) **[ASAP] Correction to “Multimodal E-Textile Enabled by One-Step Maskless Patterning of Femtosecond-Laser-Induced Graphene on Nonwoven, Knit, and Woven Textiles”**

Dongwook Yang, Han Ku Nam, Truong-Son Dinh Le, Jinwook Yeo, Younggeun Lee, Young-Ryeul Kim, Seung-Woo Kim, Hak-Jong Choi, Hyung Cheoul Shim, Seunghwa Ryu, Soongeun Kwon, and Young-Jin KimACS NanoDOI: 10.1021/acsnano.3c09996

**[ASAP] Crosstalk-Free Position Mapping for One-Step Reconstruction of Surface Topological Information via Eigenfrequency-Registered Wearable Interface**

Dan Fang, Sen Ding, Qian Zhou, Dazhe Zhao, Junwen Zhong, and Bingpu ZhouACS NanoDOI: 10.1021/acsnano.3c11080

**[ASAP] Synergetic Enhancement of Quantum Yield and Exciton Lifetime of Monolayer WS2 by Proximal Metal Plate and Negative Electric Bias**

Trang Thu Tran, Yongjun Lee, Shrawan Roy, Thi Uyen Tran, Youngbum Kim, Takashi Taniguchi, Kenji Watanabe, Milorad V. Milošević, Seong Chu Lim, Andrey Chaves, Joon I. Jang, and Jeongyong KimACS NanoDOI: 10.1021/acsnano.3c05667

**[ASAP] Atomic Diffusion-Induced Polarization and Superconductivity in Topological Insulator-Based Heterostructures**

Xian-Kui Wei, Abdur Rehman Jalil, Philipp Rüßmann, Yoichi Ando, Detlev Grützmacher, Stefan Blügel, and Joachim MayerACS NanoDOI: 10.1021/acsnano.3c08601

**[ASAP] Vertical Phase-Engineering MoS2 Nanosheet-Enhanced Textiles for Efficient Moisture-Based Energy Generation**

Yuan-Ming Cao, Yang Su, Mi Zheng, Peng Luo, Yang-Biao Xue, Bin-Bin Han, Min Zheng, Zuoshan Wang, Liang-Sheng Liao, and Ming-Peng ZhuoACS NanoDOI: 10.1021/acsnano.3c08132

**[ASAP] Topological Learning for the Classification of Disorder: An Application to the Design of Metasurfaces**

Tristan Madeleine, Nina Podoliak, Oleksandr Buchnev, Ingrid Membrillo Solis, Tetiana Orlova, Maria van Rossem, Malgosia Kaczmarek, Giampaolo D’Alessandro, and Jacek BrodzkiACS NanoDOI: 10.1021/acsnano.3c08776

**[ASAP] Regulated Behavior in Living Cells with Highly Aligned Configurations on Nanowrinkled Graphene Oxide Substrates: Deep Learning Based on Interplay of Cellular Contact Guidance**

Rowoon Park, Moon Sung Kang, Gyeonghwa Heo, Yong Cheol Shin, Dong-Wook Han, and Suck Won HongACS NanoDOI: 10.1021/acsnano.2c09815