Found 58 papers in cond-mat The phenomena of superconductivity and charge density waves are observed in
close vicinity in many strongly correlated materials. Increasing evidence from
experiments and numerical simulations suggests both phenomena can also occur in
an intertwined manner, where the superconducting order parameter is coupled to
the electronic density. Employing density matrix renormalization group
simulations, we investigate the nature of such an intertwined state of matter
stabilized in the phase diagram of the elementary $t$-$t^\prime$-$U$ Hubbard
model in the strong coupling regime. Remarkably, the condensate of Cooper pairs
is shown to be fragmented in the presence of a charge density wave where more
than one pairing wave function is macroscopically occupied. Moreover, we
provide conclusive evidence that the macroscopic wave functions of the
superconducting fragments are well-described by soliton solutions of a
Ginzburg-Landau equation in a periodic potential constituted by the charge
density wave. In the presence of an orbital magnetic field, the order
parameters are gauge invariant, and superconducting vortices are pinned between
the stripes. This intertwined Ginzburg-Landau theory is proposed as an
effective low-energy description of the stripe fragmented superconductor.
Janus materials have attracted much interest due to their intrinsic electric
dipole moment which, among other consequences, triggers Rashba band splitting.
We show that, by building bilayers of MoSeTe and WSeTe with different chalcogen
atom sequences and different stacking patterns, one can modulate the net dipole
moment strength and thus the Rashba effect, as well as the band alignment of
the MoSeTe/WSeTe bilayer. Type-II band alignment is found which can be
exploited to create long-lived interlayer excitons. Moreover, it is shown that
the atomic sequence and stacking play pivotal roles in the interlayer distance
of MoSeTe/WSeTe and thus its electronic structure and vibrational, especially
low-frequency, characteristics. The long-range dispersion forces between atoms
are treated with a conventional additive pairwise, as well as a
many-body-dispersion method. It is shown that under the many-body dispersion
method, more clear and rational thermodynamic trends of bilayer stacking are
realized and interface distances are estimated more accurately. Vibrational
spectra of the bilayers are calculated using first-principles phonon
calculations and the fingerprints of monolayer attraction and repulsion are
identified. An anti-correlation between distance and the shearing mode
frequency of the rigid monolayers is demonstrated which agrees well with
experimental findings. The results suggest that the judicious selection of the
atomic sequence and stacking helps to widen the scope of the low-dimensional
materials by adding or enhancing properties for specific applications, e.g. for
spintronics or valleytronics devices.
Higher-order topological insulators (HOTIs) have attracted increasing
interest as a unique class of topological quantum materials. One distinct
property of HOTIs is the crystalline symmetry-imposed topological state at the
lower-dimensional outer boundary, e.g. the zero-dimensional (0D) corner state
of a 2D HOTI, used exclusively as a universal signature to identify
higher-order topology but yet with uncertainty. Strikingly, we discover the
existence of inner topological point states (TPS) in a 2D HOTI, as the embedded
"end" states of 1D first-order TI, as exemplified by those located at the
vacancies in a Kekule lattice. Significantly, we demonstrate that such inner
TPS can be unambiguously distinguished from the trivial point-defect states, by
their unique topology-endowed inter-TPS interaction and correlated magnetic
response in spectroscopy measurements, overcoming an outstanding experimental
challenge. Furthermore, based on first-principles calculations, we propose
{\gamma}-graphyne as a promising material to observe the higher-order TPS. Our
findings shed new light on our fundamental understanding of HOTIs, and also
open an avenue to experimentally distinguishing and tuning TPS in the interior
of a 2D sample for potential applications.
Quasicrystal (QC) has no periodicity but has a unique rotational symmetry
forbidden in periodic crystals. Lack of microscopic theory of the crystalline
electric field (CEF) in the QC and approximant crystal (AC) has prevented us
from understanding the electric property, especially the magnetism. By
developing the general formulation of the CEF in the rare-earth based QC and
AC, we have analyzed the CEF in the QC Au-SM-Tb and AC (SM=Si, Ge, and Ga). The
magnetic anisotropy arising from the CEF plays an important role in realizing
unique magnetic states on the icosahedron (IC). By constructing the minimal
model with the magnetic anisotropy, we have analyzed the ground-state
properties of the IC, 1/1 AC, and QC. The hedgehog state is characterized by
the topological charge of one and the whirling-moment state is characterized by
the topological charge of three. The uniform arrangement of the ferrimagnetic
state is stabilized in the QC with the ferromagnetic (FM) interaction, which is
a candidate for the magnetic structure recently observed FM long-range order in
the QC Au-Ga-Tb. The uniform arrangement of the hedgehog state is stabilized in
the QC with the antiferromagnetic interaction, which suggests the possibility
of the topological magnetic long-range order.
Controlled charge flows are fundamental to many areas of science and
technology, serving as carriers of energy and information, as probes of
material properties and dynamics, and as a means of revealing or even inducing
broken symmetries. Emerging methods for light-based current control offer
promising routes beyond the speed and adaptability limitations of conventional
voltage-driven systems. However, optical manipulation of currents at nanometer
spatial scales remains a basic challenge and a key step toward scalable
optoelectronic systems and local probes. Here, we introduce vectorial
optoelectronic metasurfaces as a new class of metamaterial in which ultrafast
charge flows are driven by light pulses, with actively-tunable directionality
and arbitrary patterning down to sub-diffractive nanometer scales. In the
prototypical metasurfaces studied herein, asymmetric plasmonic nanoantennas
locally induce directional, linear current responses within underlying
graphene. Nanoscale unit cell symmetries are read out via polarization- and
wavelength-sensitive currents and emitted terahertz (THz) radiation. Global
vectorial current distributions are revealed by spatial mapping of the THz
field polarization, also demonstrating the direct generation of elusive
broadband THz vector beams. We show that a detailed interplay between
electrodynamic, thermodynamic, and hydrodynamic degrees of freedom gives rise
to these currents through rapidly-evolving nanoscale forces and charge flows
under extreme spatial and temporal localization. These results set the stage
for versatile patterning and optical control over nanoscale currents in
materials diagnostics, nano-magnetism, microelectronics, and ultrafast
information science.
We study theoretically the effect of electronic interactions in 1d systems on
electron injection using periodic Lorentzian pulses, known as Levitons. We
consider specifically a system composed of a metallic single-wall carbon
nanotube, described with the Luttinger liquid formalism, a scanning tunneling
microscope (STM) tip, and metallic leads. Using the out-of-equilibrium Keldysh
Green function formalism, we compute the current and current noise in the
system. We prove that the excess noise vanishes when each Leviton injects an
integer number of electrons from the STM tip into the nanotube. This extends
the concept of minimal injection with Levitons to strongly correlated,
uni-dimensional non-chiral systems. We also study the time-dependent current
profile, and show how it is the result of interferences between pulses
non-trivially reflected at the nanotube/lead interface.
When viewed with a cross-polarized optical microscope (POM), liquid crystals
display interference colors and complex patterns that depend on the material's
microscopic orientation. That orientation can be manipulated by application of
external fields, which provides the basis for applications in optical display
and sensing technologies. The color patterns themselves have a high information
content. Traditionally, however, calculations of the optical appearance of
liquid crystals have been performed by assuming that a single-wavelength light
source is employed, and reported in a monochromatic scale. In this work, the
original Jones matrix method is extended to calculate the colored images that
arise when a liquid crystal is exposed to a multi-wavelength source. By
accounting for the material properties, the visible light spectrum and the CIE
color matching functions, we demonstrate that the proposed approach produces
colored POM images that are in quantitative agreement with experimental data.
Results are presented for a variety of systems, including radial, bipolar, and
cholesteric droplets, where results of simulations are compared to experimental
microscopy images. The effects of droplet size, topological defect structure,
and droplet orientation are examined systematically. The technique introduced
here generates images that can be directly compared to experiments, thereby
facilitating machine learning efforts aimed at interpreting LC microscopy
images, and paving the way for the inverse design of materials capable of
producing specific internal microstructures in response to external stimuli.
Fire ants (Solenopsis invicta) cohesively aggregate via the formation of
voluntary ant-to-ant attachments when under confinement or exposed to water.
Once formed, these aggregations act as viscoelastic solids due to dynamic bond
exchange between neighboring ants as demonstrated by rate-dependent mechanical
response of 3D aggregations, confined in rheometers. We here investigate the
mechanical response of 2D, planar ant rafts roughly as they form in nature.
Specifically, we load rafts under uniaxial tension to failure, as well as to
50% strain for two cycles with various recovery times between. We do so while
measuring raft reaction force (to estimate network-scale stress), as well as
the networks' instantaneous velocity fields and topological damage responses to
elucidate the ant-scale origins of global mechanics. The rafts display
brittle-like behavior even at slow strain rates (relative to the unloaded bond
detachment rate) for which Transient Network Theory predicts steady-state
creep. This provides evidence that loaded ant-to-ant bonds undergo
mechanosensitive bond stabilization or act as \say{catch bonds}. This is
further supported by the coalescence of voids that nucleate due to biaxial
stress conditions and merge due to bond dissociation. The characteristic
timescales of void coalescence due to chain dissociation provide evidence that
the local detachment of stretched bonds is predominantly strain- (as opposed to
bond lifetime-) dependent, even at slow strain rates, implying that bond
detachment rates diminish significantly under stretch. Significantly, when the
voids are closed by restoring the rafts to unstressed conditions, mechanical
recovery occurs, confirming the presence of concentration-dependent bond
association that - combined with force-diminished dissociation - could further
bolster network cohesion under certain stress states.
Understanding the nature of vortices in type-II superconductors has been
vital for deepening the physics of exotic superconductors and applying
superconducting materials to future electronic devices. A recent study has
shown that the LiTi2O4(111) thin film offers a unique experimental platform to
unveil the nature of the vortex along the curved Josephson junction. This study
successfully visualized individual Josephson vortices along the curved
Josephson junctions using in-situ spectroscopic scanning tunneling microscopy
on LiTi2O4 (111) epitaxial thin films. Notably, the local curvature of the
Josephson junction was discovered to control the position of Josephson
vortices. Furthermore, the numerical simulation reproduces the critical role of
the curvature of the Josephson junction. This study provides guidelines to
control Josephson vortices through geometrical ways, such as mechanical
controlling of superconducting materials and their devices.
We investigate the nature of quantum criticality and topological phase
transitions near the critical lines obtained for the extended Kitaev chain with
next nearest neighbor hopping parameters and non-Hermitian chemical potential.
We surprisingly find multiple gap-less points, the locations of which in the
momentum space can change along the critical line unlike the Hermitian
counterpart. The interesting simultaneous occurrences of vanishing and sign
flipping behavior by real and imaginary components, respectively of the lowest
excitation is observed near the topological phase transition. Introduction of
non- Hermitian factor leads to an isolated critical point instead of a critical
line and hence, reduced number of multi-critical points as compared to the
Hermitian case. The critical exponents obtained for the multi-critical and
critical points show a very distinct behavior from the Hermitian case.
For the first time in the world, we succeeded in synthesizing the
room-temperature superconductor (Tc above 400 K, 127 oC) working at ambient
pressure with a modified lead-apatite (LK-99) structure. The superconductivity
of LK-99 is proved with the Critical temperature (Tc), Zero-resistivity,
Critical current (Ic), Critical magnetic field (Hc), and the Meissner effect.
The superconductivity of LK-99 originates from minute structural distortion by
a slight volume shrinkage (0.48 %), not by external factors such as temperature
and pressure. The shrinkage is caused by Cu2+ substitution of Pb2+(2) ions in
the insulating network of Pb(2)-phosphate and it generates the stress. It
concurrently transfers to Pb(1) of the cylindrical column resulting in
distortion of the cylindrical column interface, which creates superconducting
quantum wells (SQWs) in the interface. The heat capacity results indicated that
the new model is suitable for explaining the superconductivity of LK-99. The
unique structure of LK-99 that allows the minute distorted structure to be
maintained in the interfaces is the most important factor that LK-99 maintains
and exhibits superconductivity at room temperatures and ambient pressure.
A material called, LK-99 a modified-lead apatite crystal structure with the
composition at (0.9<x<1.1), has been synthesized using the solid-state method.
The material exhibits the Ohmic metal characteristic of Pb(6s^1) above its
superconducting critical temperature, Tc, and the levitation phenomenon as
Meissner effect of a superconductor at room temperature and atmospheric
pressure below Tc. A LK-99 sample shows Tc above 126.85C (400 K). We analyze
that the possibility of room-temperature superconductivity in this material is
attributed to two factors: the first being the volume contraction resulting
from an insulator-metal transition achieved by substituting Pb with Cu, and the
second being on-site repulsive Coulomb interaction enhanced by the structural
deformation in the one-dimensional(D) chain along the c-axis) structure owing
to superconducting condensation at T_c. The mechanism of the room-temperature
T_c is discussed by 1-D BR-BCS theory.
We study quasi-bound states of two electrons that arise in two-dimensional
materials with a Mexican-hat dispersion (MHD) at an energy above its central
maximum. The width of the resonance of the local density of states created by
pairs is determined by the hybridization of atomic orbitals, due to which the
MHD is formed. The mechanism of the quasi-bound state formation is due to the
fact that effective reduced mass of electrons near the MHD top is negative. An
unusual feature of quasi-bound states is that the resonance width can vanish
and then they transform into bound states in continuum. We study in detail the
quasi-bound states for topological insulators, when the MHD is due to the
hybridization of inverted electron and hole bands. In this case, the resonance
width is extremely small at weak hybridization. The highest binding energy is
achieved for singlet quasi-bound pairs with zero angular number.
The valley Hall effect arises from valley contrasting Berry curvature and
requires inversion symmetry breaking. Here, we propose a nonlinear mechanism to
generate a valley Hall current in systems with both inversion and time-reversal
symmetry, where the linear and second-order Hall charge currents vanish along
with the linear valley Hall current. We show that a second-order valley Hall
signal emerges from the electric field correction to the Berry curvature,
provided a valley-contrasting anisotropic dispersion is engineered. We
demonstrate the nonlinear valley Hall effect in tilted massless Dirac fermions
in strained graphene and organic semiconductors. Our work opens up the
possibility of controlling the valley degree of freedom in inversion symmetric
systems via nonlinear valleytronics.
Quantifying electron-phonon interactions for the surface states of
topological materials can provide key insights into surface-state transport,
topological superconductivity, and potentially how to manipulate the surface
state using a structural degree of freedom. We perform time-resolved x-ray
diffraction (XRD) and angle-resolved photoemission (ARPES) measurements on
Bi$_2$Te$_3$ and Bi$_2$Se$_3$, following the excitation of coherent A$_{1g}$
optical phonons. We extract and compare the deformation potentials coupling the
surface electronic states to local A$_{1g}$-like displacements in these two
materials using the experimentally determined atomic displacements from XRD and
electron band shifts from ARPES.We find the coupling in Bi$_2$Te$_3$ and
Bi$_2$Se$_3$ to be similar and in general in agreement with expectations from
density functional theory. We establish a methodology that quantifies the
mode-specific electron-phonon coupling experimentally, allowing detailed
comparison to theory. Our results shed light on fundamental processes in
topological insulators involving electron-phonon coupling.
In this study, we investigate the charge transport properties of
semiconducting armchair graphene nanoribbons (AGNRs) and heterostructures
through their topological states (TSs), with a specific focus on the Coulomb
blockade region. Our approach employs a two-site Hubbard model that takes into
account both intra- and inter-site Coulomb interactions. Using this model, we
calculate the electron thermoelectric coefficients and tunneling currents of
serially coupled TSs (SCTSs). In the linear response regime, we analyze the
electrical conductance ($G_e$), Seebeck coefficient ($S$), and electron thermal
conductance ($\kappa_e$) of finite AGNRs. Our results reveal that at low
temperatures, the Seebeck coefficient is more sensitive to many-body spectra
than the electrical conductance. Furthermore, we observe that the optimized $S$
at high temperature is less sensitive to electron Coulomb interactions than
$G_e$ and $\kappa_e$. In the nonlinear response regime, we observe a tunneling
current with negative differential conductance through the SCTSs of finite
AGNRs. This current is generated by electron inter-site Coulomb interactions
rather than intra-site Coulomb interactions. Additionally, we observe current
rectification behavior in asymmetrical junction systems of SCTSs of AGNRs.
Notably, we also uncover the remarkable current rectification behavior of SCTSs
of 9-7-9 AGNR heterostructure in the Pauli spin blockade configuration.
Overall, our study provides valuable insights into the charge transport
properties of TSs in finite AGNRs and heterostructures. We emphasize the
importance of considering electron-electron interactions in understanding the
behavior of these materials.
The electron's kinetic energy plays a pivotal role in magnetism. While
virtual electron hopping promotes antiferromagnetism in an insulator, the real
process usually favors ferromagnetism. But in kinetically frustrated systems,
such as hole doped triangular lattice Mott insulators, real hopping has been
shown to favor antiferromagnetism. Kinetic frustration has also been predicted
to induce a new quasiparticle -- a bound state of the doped hole and a spin
flip called a spin polaron -- at intermediate magnetic fields, which could form
an unusual metallic state. However, the direct experimental observation of spin
polarons has remained elusive. Here we report the observation of spin polarons
in triangular lattice MoTe2/WSe2 moir\'e bilayers by the reflective magnetic
circular dichroism measurements. We identify a spin polaron phase at lattice
filling factor between 0.8-1 and magnetic field between 2-4 T; it is separated
from the fully spin polarized phase by a metamagnetic transition. We determine
that the spin polaron is a spin-3/2 particle and its binding energy is
commensurate to the kinetic hopping energy. Our results open the door for
exploring spin polaron pseudogap metals, spin polaron pairing and other new
phenomena in triangular lattice moir\'e materials.
The Fermi surface symmetric mass generation (SMG) is an intrinsically
interaction-driven mechanism that opens an excitation gap on the Fermi surface
without invoking symmetry-breaking or topological order. We explore this
phenomenon within a bilayer square lattice model of spin-1/2 fermions, where
the system can be tuned from a metallic Fermi liquid phase to a
strongly-interacting SMG insulator phase by an inter-layer spin-spin
interaction. The SMG insulator preserves all symmetries and has no mean-field
interpretation at the single-particle level. It is characterized by zeros in
the fermion Green's function, which encapsulate the same Fermi volume in
momentum space as the original Fermi surface, a feature mandated by the
Luttinger theorem. Utilizing both numerical and field-theoretical methods, we
provide compelling evidence for these Green's function zeros across both strong
and weak coupling regimes of the SMG phase. Our findings highlight the
robustness of the zero Fermi surface, which offers promising avenues for
experimental identification of SMG insulators through spectroscopy experiments
despite potential spectral broadening from noise or dissipation.
Intermetallics are an important playground to stabilize a large variety of
physical phenomena, arising from their complex crystal structure. The ease of
their chemical tuneabilty makes them suitable platforms to realize targeted
electronic properties starting from the symmetries hidden in their unit cell.
Here, we investigate the family of the recently discovered intermetallics
MCo$_2$Al$_9$ (M: Sr, Ba) and we unveil their electronic structure for the
first time. By using angle-resolved photoelectron spectroscopy and density
functional theory calculations, we discover the existence of Dirac-like
dispersions as ubiquitous features in this family, coming from the hidden
kagome and honeycomb symmetries embedded in the unit cell. Finally, from
calculations, we expect that the spin-orbit coupling is responsible for opening
energy gaps in the electronic structure spectrum, which also affects the
majority of the observed Dirac-like states. Our study constitutes the first
experimental observation of the electronic structure of MCo$_2$Al$_9$ and
proposes these systems as hosts of Dirac-like physics with intrinsic spin-orbit
coupling. The latter effect suggests MCo$_2$Al$_9$ as a future platform for
investigating the emergence of non-trivial topology.
The quantization of conductance in the presence of non-magnetic point defects
is a consequence of topological protection and the spin-momentum locking of
helical edge states in two-dimensional topological insulators. This protection
ensures the absence of backscattering of helical edge modes in the quantum Hall
phase of the system. However, our study focuses on exploring a novel approach
to disrupt this protection. We propose that a linear arrangement of on-site
impurities can effectively lift the topological protection of edge states in
the Kane-Mele model. To investigate this phenomenon, we consider an armchair
ribbon containing a line defect spanning its width. Utilizing the tight-binding
model and non-equilibrium Green's function method, we calculate the
transmission coefficient of the system. Our results reveal a suppression of
conductance at energies near the lower edge of the bulk gap for positive
on-site potentials. To further comprehend this behavior, we perform analytical
calculations and discuss the formation of an impurity channel. This channel
arises due to the overlap of in-gap bound states, linking the bottom edge of
the ribbon to its top edge, consequently facilitating backscattering. Our
explanation is supported by the analysis of the local density of states at
sites near the position of impurities.
Quantum spin liquids are tantalizing phases of frustrated quantum magnets. A
complicating factor in their realization and observation in materials is the
ubiquitous presence of other degrees of freedom, in particular lattice
distortion modes (phonons). These provide additional routes for relieving
magnetic frustration, thereby possibly destabilizing spin-liquid ground states.
In this work, we focus on triangular-lattice Heisenberg antiferromagnets, where
recent numerical evidence suggests the presence of an extended U(1) Dirac spin
liquid phase which is described by compact quantum electrodynamics in 2+1
dimensions (QED$_3$), featuring gapless spinons and monopoles as gauge
excitations. Its low energy theory is believed to flow to a strongly-coupled
fixed point with conformal symmetries. Using complementary perturbation theory
and scaling arguments, we show that a symmetry-allowed coupling between
(classical) finite-wavevector lattice distortions and monopole operators of the
U(1) Dirac spin liquid generally induces a spin-Peierls instability towards a
(confining) 12-site valence-bond solid state. We support our theoretical
analysis with state-of-the-art density matrix renormalization group
simulations. Away from the limit of static distortions, we demonstrate that the
phonon energy gap establishes a parameter regime where the spin liquid is
expected to be stable.
We study the Rouse-type dynamics of elastic fractal networks with embedded,
stochastically driven, active force monopoles and dipoles, that are temporally
correlated. We compute, analytically -- using a general theoretical framework
-- and via Langevin dynamics simulations, the mean square displacement of a
network bead. Following a short-time super-diffusive behavior, force monopoles
yield anomalous subdiffusion with an exponent identical to that of the thermal
system. Force dipoles do not induce subdiffusion, and result in rotational
motion of the whole network -- as found for micro-swimmers -- and network
collapses beyond a critical force amplitude. The collapse persists with
increasing system size, signifying a true first-order dynamical phase
transition. We conclude that the observed identical subdiffusion exponents of
chromosomal loci in normal and ATP-depleted cells are attributed to active
force monopoles rather than force dipoles.
Discovering the nonlinear transport features in antiferromagnets is of
fundamental interest in condensed matter physics as it offers a new frontier of
the understanding deep connections between multiple degrees of freedom,
including magnetic orders, symmetries, and band geometric properties.
Antiferromagnetic topological insulator MnBi${_2}$Te${_4}$ has provided a
highly tunable platform for experimental explorations due to its rich magnetic
structures and striking topological band structures. Here, we experimentally
investigate the third-order nonlinear transport properties in bulk
MnBi${_2}$Te${_4}$ flakes. The measured third-harmonic longitudinal
($V_{xx}^{3{\omega}}$) and transverse ($V_{xy}^{3{\omega}}$) voltages show
intimate connection with magnetic transitions of MnBi${_2}$Te${_4}$ flakes and
their magnitudes change abruptly as MnBi${_2}$Te${_4}$ flakes go through
magnetic transitions with varying temperature and magnetic fields. In addition,
the measured $V_{xx}^{3{\omega}}$ exhibits an even-symmetric feature with
changing magnetic field direction and the $V_{xy}^{3{\omega}}$ shows an
odd-symmetric property, which are believed to be related to the quantum metric
and the emergency of non-zero Berry curvature quadrupole with broken ${PT}$
symmetry and non-degenerate band structures under external magnetic fields,
respectively. Our work shows great advances in the understanding of the
underlying interactions between multiple geometric quantities.
We analyze a setup composed of a correlated quantum dot (QD) coupled to one
metallic lead and one end of topological chain hosting a Majorana zero mode
(MZM). In such a hybrid structure, a leakage of the MZM into the region of the
QD competes with the Kondo resonance appearing as a consequence of the
spin-exchange interactions between the dot and the lead. In the work, we use
the nontrivial technique called the continuous unitary transformation (CUT) to
analyze this competition. Using the CUT technique, we inspect the influence of
the coupling between the QD and the chain on effective exchange interactions
and calculate the resultant Kondo temperature.
Knitting interloops one-dimensional yarns into three-dimensional fabrics that
exhibit behaviours beyond their constitutive materials. How extensibility and
anisotropy emerge from the hierarchical organization of yarns into knitted
fabrics has long been unresolved. We sought to unravel the mechanical roles of
tensile mechanics, assembly and dynamics arising from the yarn level on fabric
nonlinearity by developing a yarn-based dynamical model. This physically
validated model captures the fundamental mechanical response of knitted
fabrics, analogous to flexible metamaterials and biological fiber networks due
to geometric nonlinearity within such hierarchical systems. We identify the
dictating factors of the mechanics of knitted fabrics, highlighting the
previously overlooked but critical effect of pre-tension. Fabric anisotropy
originates from observed yarn--yarn rearrangements during alignment dynamics
and is topology-dependent. This yarn-based model also provides design
flexibility of knitted fabrics to embed functionalities by allowing variation
in both geometric configuration and material property. Our hierarchical
approach to build up a knitted fabrics computationally modernizes an ancient
craft and represents a first step towards mechanical programmability of knitted
fabrics in wide engineering applications.
Topological magnons have received substantial interest for their potential in
both fundamental research and device applications due to their exotic uncharged
yet topologically protected boundary modes. However, their understanding has
been impeded by the lack of fundamental symmetry descriptions of magnetic
materials, of which the spin Hamiltonians are essentially determined by the
isotropic Heisenberg interaction. The corresponding magnon band structures
allows for more symmetry operations with separated spin and spatial operations,
forming spin space groups (SSGs), than the conventional magnetic space groups.
Here we developed spin space group (SSG) theory to describe collinear magnetic
configurations, identifying all the 1421 collinear SSGs and categorizing them
into four types, constructing band representations for these SSGs, and
providing a full tabulation of SSGs with exotic nodal topology. Our
representation theory perfectly explains the band degeneracies of previous
experiments and identifies new magnons beyond magnetic space groups with
topological charges, including duodecuple point, octuple nodal line and
charge-4 octuple point. With an efficient algorithm that diagnoses topological
magnons in collinear magnets, our work offers new pathways to exploring exotic
phenomena of magnonic systems, with the potential to advance the
next-generation spintronic devices.
In an altermagnet, the symmetry that relates configurations with flipped
magnetic moments is a rotation. This makes it qualitatively different from a
ferromagnet, where no such symmetry exists, or a collinear antiferromagnet,
where this symmetry is a lattice translation. In this paper, we investigate the
impact of the crystalline environment on the magnetic and electronic properties
of an altermagnet. We find that, because each component of the magnetization
acquires its own angular dependence, the Zeeman splitting of the bands has
symmetry-protected nodal lines residing on mirror planes of the crystal. Upon
crossing the Fermi surface, these nodal lines give rise to pinch points that
behave as single or double type-II Weyl nodes. We show that an external
magnetic field perpendicular to these mirror planes can only move the nodal
lines, such that a critical field value is necessary to collapse the nodes and
make the Weyl pinch points annihilate. This unveils the topological nature of
the transition from a nodal to a nodeless Zeeman splitting of the bands. We
also classify the altermagnetic states of common crystallographic point groups
in the presence of spin-orbit coupling, revealing that a broad family of
magnetic orthorhombic perovskites can realize altermagnetism.
We explore a hexagonal cavity that supports chiral topological whispering
gallery (CTWG) modes, formed by a gyromagnetic photonic crystal. This mode is a
special type of topologically protected optical mode that can propagate in
photonic crystals with chiral direction. Finite element method simulations show
that discrete edge states exist in the topological band gap due to the coupling
of chiral edge states and WG modes. Since the cavity only supports edge state
modes with group velocity in only one direction, it can purely generate
traveling modes and be immune to interference modes. In addition, we introduced
defects and disorder to test the robustness of the cavity, demonstrating that
the CTWG modes can be effectively maintained under all types of perturbations.
Our topological cavity platform offers useful prototype of robust topological
photonic devices. The existence of this mode can have important implications
for the design and application of optical devices.
Topological phases are greatly enriched by including non-Hermiticity. While
most works focus on the topology of the eigenvalues and eigenstates, how
topologically nontrivial non-Hermitian systems behave in dynamics has only
drawn limited attention. Here, we consider a breathing honeycomb lattice known
to emulate the quantum spin Hall effect and exhibits higher-order corner modes.
We find that non-reciprocal intracell couplings introduce gain in one
pseudo-spin subspace while loss with the same magnitude in the other. In
addition, non-reciprocal intracell couplings can also suppress the spin mixture
of the edge modes at the boundaries and delocalize the higher-order corner
mode. Our findings deepen the understanding of non-Hermitian topological phases
and bring in the spin degree of freedom in manipulating the dynamics in
non-Hermitian systems.
The algebraic tools used to study topological phases of matter are not
clearly suited to studying processes in which the bulk energy gap closes, such
as phase transitions. We describe an elementary two edge thought experiment
which reveals the effect of an anyon condensation phase transition on the
robust edge properties of a sample, bypassing a limitation of the algebraic
description. In particular, the two edge construction allows some edge degrees
of freedom to be tracked through the transition, despite the bulk gap closing.
The two edge model demonstrates that bulk anyon condensation induces symmetry
breaking in the edge model. Further, the construction recovers the expected
result that the number of chiral current carrying modes at the edge cannot
change through anyon condensation. We illustrate the construction through
detailed analysis of anyon condensation transitions in an achiral phase, the
toric code, and in chiral phases, the Kitaev spin liquids.
We study the relation between the quantum geometry of wave functions and the
Landau level (LL) spectrum of two-band Hamiltonians with a quadratic band
crossing point (QBCP) in two-dimensions. By investigating the influence of
interband coupling parameters on the wave function geometry of general QBCPs,
we demonstrate that the interband coupling parameters can be entirely
determined by the projected elliptic image of the wave functions on the Bloch
sphere, which can be characterized by three parameters, i.e., the major $d_1$
and minor $d_2$ diameters of the ellipse, and one angular parameter $\phi$
describing the orientation of the ellipse. These parameters govern the
geometric properties of the system such as the Berry phase and modified LL
spectra. Explicitly, by comparing the LL spectra of two quadratic band models
with and without interband couplings, we show that the product of $d_1$ and
$d_2$ determines the constant shift in LL energy while their ratio governs the
initial LL energies near a QBCP. Also, by examining the influence of the
rotation and time-reversal symmetries on the wave function geometry, we
construct a minimal continuum model which exhibits various wave function
geometries. We calculate the LL spectra of this model and discuss how interband
couplings give LL structure for dispersive bands as well as nearly flat bands.
We introduce a set of axioms for locally topologically ordered quantum spin
systems in terms of nets of local ground state projections, and we show they
are satisfied by Kitaev's Toric Code and Levin-Wen type models. Then for a
locally topologically ordered spin system on $\mathbb{Z}^{k}$, we define a
local net of boundary algebras on $\mathbb{Z}^{k-1}$, which gives a new
operator algebraic framework for studying topological spin systems. We
construct a canonical quantum channel so that states on the boundary
quasi-local algebra parameterize bulk-boundary states without reference to a
boundary Hamiltonian. As a corollary, we obtain a new proof of a recent result
of Ogata [arXiv:2212.09036] that the bulk cone von Neumann algebra in the Toric
Code is of type $\rm{II}$, and we show that Levin-Wen models can have cone
algebras of type $\rm{III}$. Finally, we argue that the braided tensor category
of DHR bimodules for the net of boundary algebras characterizes the bulk
topological order in (2+1)D, and can also be used to characterize the
topological order of boundary states.
Developing behavioral policies designed to efficiently solve target-search
problems is a crucial issue both in nature and in the nanotechnology of the
21st century. Here, we characterize the target-search strategies of simple
microswimmers in a homogeneous environment containing sparse targets of unknown
positions. The microswimmers are capable of controlling their dynamics by
switching between Brownian motion and an active Brownian particle and by
selecting the time duration of each of the two phases. The specific conduct of
a single microswimmer depends on an internal decision-making process determined
by a simple neural network associated with the agent itself. Starting from a
population of individuals with random behavior, we exploit the genetic
algorithm NeuroEvolution of Augmenting Topologies to show how an evolutionary
pressure based on the target-search performances of single individuals helps to
find the optimal duration of the two different phases. Our findings reveal that
the optimal policy strongly depends on the magnitude of the particle's
self-propulsion during the active phase and that a broad spectrum of network
topology solutions exists, differing in the number of connections and hidden
nodes.
It has been widely believed that almost all states in one-dimensional (1d)
disordered systems with short-range hopping and uncorrelated random potential
are localized. Here, we consider the fate of these localized states by coupling
between a disordered chain (with localized states) and a free chain (with
extended states), showing that states in the overlapped and un-overlapped
regimes exhibit totally different localization behaviors, which is not a phase
transition process. In particular, while states in the overlapped regime are
localized by resonant coupling, in the un-overlapped regime of the free chain,
significant suppression of the localization with a prefactor of $\xi^{-1}
\propto t_v^4/\Delta^4$ appeared, where $t_v$ is the inter-chain coupling
strength and $\Delta$ is the energy shift between them. This system may exhibit
localization lengths that are comparable with the system size even when the
potential in the disordered chain is strong. We confirm these results using the
transfer matrix method and sparse matrix method for systems $L \sim 10^6 -
10^9$. These findings extend our understanding of localization in
low-dimensional disordered systems and provide a concrete example, which may
call for much more advanced numerical methods in high-dimensional models.
Despite the rapid pace of computationally and experimentally discovering new
two-dimensional layered materials, a general criteria for a given compound to
prefer a layered structure over a non-layered one remains unclear. Articulating
such criteria would allow one to identify materials at the verge of an
inter-dimensional structural phase transition between a 2D layered phase and 3D
bulk one, with potential applications in phase change memory devices. Here we
identify a general stabilization effect driven by vibrational entropy that can
favor 2D layered structures over 3D bulk structures at higher temperatures,
which can manifest in ordered vacancy compounds where phase competition is
tight. We demonstrate this vibrational-entropy stabilization effect for three
prototypical ordered vacancy chalcogenides, ZnIn2S4 and In2S3, and Cu3VSe4,
either by vacancy rearrangement or by cleaving through existing vacancies. The
relative vibrational entropy advantage of the 2D layered phase originates
mainly from softened out-of-plane dilation phonon modes.
We perform micro-photoluminescence and Raman experiments to examine the
impact of biaxial tensile strain on the optical properties of WS2 monolayers. A
strong shift on the order of -130 meV per % of strain is observed in the
neutral exciton emission at room temperature. Under near-resonant excitation we
measure a monotonic decrease in the circular polarization degree under applied
strain. We experimentally separate the effect of the strain-induced energy
detuning and evaluate the pure effect coming from biaxial strain. The analysis
shows that the suppression of the circular polarization degree under biaxial
strain is related to an interplay of energy and polarization relaxation
channels as well as to variations in the exciton oscillator strength affecting
the long-range exchange interaction.
Excitonic states trapped in harmonic moir\'e wells of twisted heterobilayers
is an intriguing testbed. However, the moir\'e potential is primarily governed
by the twist angle, and its dynamic tuning remains a challenge. Here we
demonstrate anharmonic tuning of moir\'e potential in a WS$_2$/WSe$_2$
heterobilayer through gate voltage and optical power. A gate voltage can result
in a local in-plane perturbing field with odd parity around the high-symmetry
points. This allows us to simultaneously observe the first (linear) and second
(parabolic) order Stark shift for the ground state and first excited state,
respectively, of the moir\'e trapped exciton - an effect opposite to
conventional quantum-confined Stark shift. Depending on the degree of
confinement, these excitons exhibit up to twenty-fold gate-tunability in the
lifetime ($100$ to $5$ ns). Also, exciton localization dependent dipolar
repulsion leads to an optical power-induced blueshift of $\sim$1 meV/$\mu$W - a
five-fold enhancement over previous reports.
In quasi-two-dimensional experiments with photoelastic particles confined to
an annular region, an intruder constrained to move in a circular path halfway
between the annular walls experiences stick-slip dynamics. We discuss the
response of the granular medium to the driven intruder, focusing on the
evolution of the force network during sticking periods. Because the available
experimental data does not include precise information about individual contact
forces, we use an approach developed in our previous work (Basak et al, J. Eng.
Mechanics (2021)) based on networks constructed from measurements of the
integrated strain magnitude on each particle. These networks are analyzed using
topological measures based on persistence diagrams, revealing that force
networks evolve smoothly but in a nontrivial manner throughout each sticking
period, even though the intruder and granular particles are stationary.
Characteristic features of persistence diagrams show identifiable changes as a
slip is approaching, indicating the existence of slip precursors. Key features
of the dynamics are similar for granular materials composed of disks or
pentagons, but some details are consistently different. In particular, we find
significantly larger fluctuations of the measures computed based on persistence
diagrams, and therefore of the underlying networks, for systems of pentagonal
particles.
We describe the interplay between electric-magnetic duality and higher
symmetry in Maxwell theory. When the fine-structure constant is rational, the
theory admits non-invertible symmetries which can be realized as composites of
electric-magnetic duality and gauging a discrete subgroup of the one-form
global symmetry. These non-invertible symmetries are approximate quantum
invariances of the natural world which emerge in the infrared below the mass
scale of charged particles. We construct these symmetries explicitly as
topological defects and illustrate their action on local and extended
operators. We also describe their action on boundary conditions and illustrate
some consequences of the symmetry for Hilbert spaces of the theory defined in
finite volume.
Thermal rectifiers are devices that have different thermal conductivities in
opposing directions of heat flow. The realization of practical thermal
rectifiers relies significantly on a sound understanding of the underlying
mechanisms of asymmetric heat transport, and two-dimensional materials offer a
promising opportunity in this regard owing to their simplistic structures
together with a vast possibility of tunable imperfections. However, the
in-plane thermal rectification mechanisms in 2D materials like graphene having
directional gradients of grain sizes have remained elusive. In fact,
understanding the heat transport mechanisms in polycrystalline graphene, which
are more practical to synthesize than large-scale single-crystal graphene,
could potentially allow a unique opportunity to combine with other defects and
designs for effective optimization of the thermal rectification property. In
this work, we investigated the thermal rectification behavior in periodic
atomistic models of polycrystalline graphene whose grain arrangements were
generated semi-stochastically in order to have different gradient grain-density
distributions along the in-plane heat flow direction. We employed the centroid
Voronoi tessellation technique to generate realistic grain boundary structures
for graphene, and the non-equilibrium molecular dynamics simulations method was
used to calculate the thermal conductivities and thermal rectification values.
Additionally, detailed phonon characteristics and propagating phonon spatial
energy densities were analyzed based on the fluctuation-dissipation theory to
elucidate the competitive interplay between two underlying mechanisms that
determine the degree of asymmetric heat flow in graded polycrystalline
graphene.
Collective cell migration in epithelia relies on cell intercalation: i.e. a
local remodelling of the cellular network that allows neighbouring cells to
swap their positions. While in common with foams and other passive cellular
fluids, intercalation in epithelia crucially depends on active processes, where
the local geometry of the network and the contractile forces generated therein
conspire to produce an ``avalanche'' of remodelling events, which collectively
give rise to a vortical flow at the mesoscopic length scale. In this article we
formulate a continuum theory of the mechanism driving this process, built upon
recent advances towards understanding the hexatic (i.e. $6-$fold ordered)
structure of epithelial layers. Using a combination of active hydrodynamics and
cell-resolved numerical simulations, we demonstrate that cell intercalation
takes place via the unbinding of topological defects, naturally initiated by
fluctuations and whose late-times dynamics is governed by the interplay between
passive attractive forces and active self-propulsion. Our approach sheds light
on the structure of the cellular forces driving collective migration in
epithelia and provides an explanation of the observed extensile activity of in
vitro epithelial layers.
Ultrafast laser pump-probe spectroscopy is an important and growing field of
physical chemistry that allows the measurement of chemical dynamics on their
natural timescales, but undergraduate laboratory courses lack examples of such
spectroscopy and the interpretation of the dynamics that occur. Here we develop
and implement an ultrafast pump probe spectroscopy experiment for the
undergraduate physical chemistry laboratory course at the University of
California Berkeley. The goal of the experiment is to expose students to
concepts in solid-state chemistry and ultrafast spectroscopy via classic
coherent phonon dynamics principles developed by researchers over multiple
decades. The experiment utilizes a modern high-repetition-rate 800 nm
femtosecond Ti:Sapphire laser, split pulses with a variable time delay, and
sensitive detection of transient reflectivity signals using the lock-in
technique. The experiment involves minimal intervention from students and is
therefore easy and safe to implement in the laboratory. Students first perform
an intensity autocorrelation measurement on the femtosecond laser pulses to
obtain their temporal duration. Then, students measure the pump-probe
reflectivity of a single-crystal antimony sample to determine the period of
coherent phonon oscillations initiated by an ultrafast pulse excitation, which
is analyzed by fitting to a sine wave. Students who completed the experiment
in-person obtained good experimental results, and students who took the course
remotely due to the COVID-19 pandemic were provided with the data they would
have obtained during the experiment to analyze. Evaluation of student written
and oral reports reveals that the learning goals were met, and that students
gained an appreciation for the field of ultrafast laser-induced chemistry.
Given the algebraic data characterizing any (2+1)D bosonic or fermionic
topological order with a global symmetry group $G = \mathrm{U}(1) \rtimes H$,
we construct a (3+1)D topologically invariant path integral in the presence of
a curved background $G$ gauge field, as an exact combinatorial state sum.
Specifically, the $\mathrm{U}(1)$ component of the $G$ gauge field can have a
non-trivial second Chern class, extending previous work that was restricted to
flat $G$ bundles. Our construction expresses the $\mathrm{U}(1)$ gauge field in
terms of a Villain formulation on the triangulation, which includes a 1-form
$\mathbb{R}$ gauge field and 2-form $\mathbb{Z}$ gauge field. We develop a new
graphical calculus for anyons interacting with "Villain symmetry defects",
associated with the 1-form and 2-form background gauge fields. This graphical
calculus is used to define the (3+1)D path integral, which can describe either
a bosonic or fermionic symmetry-protected topological (SPT) phase. For example,
we can construct the topological path integral on curved $\mathrm{U}(1)$
bundles for the (3+1)D fermionic topological insulator in class AII and
topological superconductor in class AIII given appropriate (2+1)D fermionic
symmetry fractionalization data; these then give invariants of 4-manifolds with
Spin$^c$ or Pin$^c$ structures and their generalizations. The (3+1)D path
integrals define anomaly indicators for the (2+1)D topological orders; in the
case of Abelian (2+1)D topological orders, we derive by explicit computation
all of the mixed $\mathrm{U}(1)$ anomaly indicator formulas proposed by Lapa
and Levin. We also propose a Spin$^c$ generalization of the Gauss-Milgram sum,
valid for super-modular categories.
Kitaev's quantum double model is a lattice gauge theoretic realization of
Dijkgraaf-Witten topological quantum field theory (TQFT), its topologically
protected ground state space has broad applications for topological quantum
computation and topological quantum memory. We investigate the $\mathbb{Z}_2$
symmetry enriched generalization of the model for the cyclic Abelian group in a
categorical framework and present an explicit Hamiltonian construction. This
model provides a lattice realization of the $\mathbb{Z}_2$ symmetry enriched
topological (SET) phase. We discuss in detail the categorical symmetry of the
phase, for which the electric-magnetic (EM) duality symmetry is a special case.
The aspects of symmetry defects are investigated using the $G$-crossed unitary
braided fusion category (UBFC). By determining the corresponding anyon
condensation, the gapped boundaries and boundary-bulk duality are also
investigated. Then we carefully construct the explicit lattice realization of
EM duality for these SET phases.
Interferometry is a powerful technique used to extract valuable information
about the wave function of a system. In this work, we study the response of
spin carriers to the effective field textures developed in curved
one-dimensional interferometric circuits subject to the joint action of Rashba
and Dresselhaus spin-orbit interactions. By using a quantum network technique,
we establish that the interplay between these two non-Abelian fields and the
circuit's geometry modify the geometrical characteristics of the spinors,
particularly on square circuits, leading to the localisation of the electronic
wave function and the suppression of the quantum conductance. We propose a
topological interpretation by classifying the corresponding spin textures in
terms of winding numbers.
Moir\'e systems made from stacked two-dimensional materials host novel
correlated and topological states that can be electrically controlled via
applied gate voltages. We have used this technique to manipulate Chern domains
in an interaction-driven quantum anomalous Hall insulator made from twisted
monolayer-bilayer graphene (tMBLG). This has allowed the wavefunction of chiral
interface states to be directly imaged using a scanning tunneling microscope
(STM). To accomplish this tMBLG carrier concentration was tuned to stabilize
neighboring domains of opposite Chern number, thus providing topological
interfaces completely devoid of any structural boundaries. STM tip
pulse-induced quantum dots were utilized to induce new Chern domains and
thereby create new chiral interface states with tunable chirality at
predetermined locations. Theoretical analysis confirms the chiral nature of
observed interface states and enables the determination of the characteristic
length scale of valley polarization reversal across neighboring tMBLG Chern
domains. tMBLG is shown to be a useful platform for imaging the exotic
topological properties of correlated moir\'e systems.
Two-dimensional (2D) van der Waals (vdW) magnetic $3d$-transition metal
trihalides are a new class of functional materials showing exotic physical
properties useful for spintronic and memory storage applications. In this
article, we report the synthesis and electromagnetic characterization of
single-crystalline vanadium trichloride, VCl$_3$, a novel 2D layered vdW Mott
insulator, which has a rhombohedral structure (R$\overline{3}$, No. 148) at
room temperature. VCl$_3$ undergoes a structural phase transition at 103 K and
a subsequent antiferromagnetic transition at 21.8 K. Combining core levels and
valence bands x-ray photoemission spectroscopy (XPS) with first-principles
density functional theory (DFT) calculations, we demonstrate the Mott Hubbard
insulating nature of VCl$_3$ and the existence of electron small 2D magnetic
polarons localized on V atom sites by V-Cl bond relaxation. The polarons
strongly affect the electromagnetic properties of VCl$_3$ promoting the
occupation of dispersion-less spin-polarized V-3d $a_{1g}$ states and band
inversion with $e^{'}_{g}$ states. Within the polaronic scenario, it is
possible to reconcile different experimental evidences on vanadium trihalides,
suggesting that also VI$_3$ hosts polarons. Our results highlight the complex
physical behavior of this class of crystals determined by charge trapping,
lattice distortions, correlation effects, mixed valence states, and magnetic
states.
The nitrogen-vacancy (NV) center in diamond has enabled studies of nanoscale
nuclear magnetic resonance (NMR) and electron paramagnetic resonance with high
sensitivity in small sample volumes. Most NV-detected NMR (NV-NMR) experiments
are performed at low magnetic fields. While low fields are useful in many
applications, high-field NV-NMR with fine spectral resolution, high signal
sensitivity, and the capability to observe a wider range of nuclei is
advantageous for surface detection, microfluidic, and condensed matter studies
aimed at probing micro- and nanoscale features. However, only a handful of
experiments above 1 T were reported. Herein, we report $^{13}$C NV-NMR
spectroscopy at 4.2 T, where the NV Larmor frequency is 115 GHz. Using an
electron-nuclear double resonance technique, we successfully detect NV-NMR of
two diamond samples. The analysis of the NMR linewidth based on the dipolar
broadening theory of Van Vleck shows that the observed linewidths from sample 1
are consistent with the intrinsic NMR linewidth of the sample. For sample 2 we
find a narrower linewidth of 44 ppm. This work paves the way for new
applications of nanoscale NV-NMR.
Electrical control of magnetism has been a major techonogical pursuit of the
spintronics community, owing to its far-reaching implications for data storage
and transmission. Here, we propose and analyze a new mechanism for electrical
switching of isospin, using chiral-stacked graphene multilayers, such as bernal
bilayer graphene or rhombohedral trilayer graphene, encapsulated by transition
metal dichalcogenide (TMD) substrates. Leveraging the proximity-induced
spin-orbit coupling from the TMD, we demonstrate electrical switching of
correlation-induced spin and/or valley polarization, by reversing a
perpendicular displacement field or the chemical potential. We substantiate our
proposal with both analytical arguments and self-consistent Hartree-Fock
numerics. Finally, we illustrate how the relative alignment of the TMDs,
together with the top and bottom gate voltages, can be used to selectively
switch distinct isospin flavors, putting forward correlated van der Waals
heterostructures as a promising platform for spintronics and valleytronics.
Neutral-atom arrays trapped in optical potentials are a powerful platform for
studying quantum physics, combining precise single-particle control and
detection with a range of tunable entangling interactions. For example, these
capabilities have been leveraged for state-of-the-art frequency metrology as
well as microscopic studies of entangled many-particle states. In this work, we
combine these applications to realize spin squeezing - a widely studied
operation for producing metrologically useful entanglement - in an optical
atomic clock based on a programmable array of interacting optical qubits. In
this first demonstration of Rydberg-mediated squeezing with a neutral-atom
optical clock, we generate states that have almost 4 dB of metrological gain.
Additionally, we perform a synchronous frequency comparison between independent
squeezed states and observe a fractional frequency stability of $1.087(1)\times
10^{-15}$ at one-second averaging time, which is 1.94(1) dB below the standard
quantum limit, and reaches a fractional precision at the $10^{-17}$ level
during a half-hour measurement. We further leverage the programmable control
afforded by optical tweezer arrays to apply local phase shifts in order to
explore spin squeezing in measurements that operate beyond the relative
coherence time with the optical local oscillator. The realization of this
spin-squeezing protocol in a programmable atom-array clock opens the door to a
wide range of quantum-information inspired techniques for optimal phase
estimation and Heisenberg-limited optical atomic clocks.
Spin triplet superconductor UTe$_{2}$ is widely believed to host a
quasi-two-dimensional Fermi surface, revealed by first principal calculations,
photoemission and quantum oscillation measurements. An outstanding question
still remains as to the existence of a three-dimensional Fermi surface pocket,
which is crucial for our understanding of the exotic superconducting and
topological properties of UTe$_{2}$. This 3D Fermi surface pocket appears in
various theoretical models with different physics origins but has not been
detected experimentally. Here for the first time, we provide concrete evidence
for a relatively isotropic, small Fermi surface pocket of UTe$_{2}$ via quantum
oscillation measurements. In addition, we observed high frequency quantum
oscillations corresponding to electron-hole tunneling between adjacent electron
and hole pockets. The coexistence of 2D and 3D Fermi surface pockets, as well
as the breakdown orbits, provides a test bed for theoretical models and aid the
realization of a unified understanding of superconducting state of UTe$_{2}$
from the first-principles approach.
The interplay between non-Hermitian effects and topological insulators has
become a frontier of research in non-Hermitian physics. However, the existence
of a non-Hermitian skin effect for topological-protected edge states remains
controversial. In this paper, we discover an alternative form of the
non-Hermitian skin effect called the non-Hermitian chiral skin effect (NHCSE).
NHCSE is a non-Hermitian skin effect under periodic boundary condition rather
than open boundary condition. Specifically, the chiral modes of the NHCSE
localize around \textquotedblleft topological defects\textquotedblright
characterized by global dissipation rather than being confined to the system
boundaries. We show its detailed physical properties by taking the
non-Hermitian Haldane model as an example. As a result, the intrinsic mechanism
of the hybrid skin-topological effect in Chern insulators is fully understood
via NHCSE. Therefore, this progress will be helpful for solving the
controversial topic of hybrid skin-topological effect and thus benefit the
research on both non-Hermitian physics and topological quantum states.
We investigate the effects of single, multiple, and extended defects in the
form of non-magnetic impurities and vacancies in twisted bilayer graphene (TBG)
at and away from the magic angle, using a fully atomistic model and focusing on
the behavior of the flat low-energy moir\'e bands. For strong impurities and
vacancies in the $AA$ region we find a complete removal of one of the four
moir\'e bands, resulting in a significant depletion of the charge density in
the $AA$ regions even at extremely low defect concentrations. We find similar
results for other defect locations, with the exception of the least coordinated
sites in the $AB$ region, where defects instead result in a peculiar band
replacement process within the moir\'e bands. In the vacancy limit, this
process yields a band structure misleadingly similar to the pristine case.
Moreover, we show that triple point fermions (TPFs), which are the crossing of
the Dirac point by a flat band, appearing for single, periodic, defects, are
generally not preserved when adding extended or multiple defects, and thus
likely not experimentally relevant. We further identify two universal length
scales for defects, consisting of charge modulations on the atomic scale and on
the moir\'e scale, illustrating the importance of both the atomic and moir\'e
structures for understanding TBG. We show that our conclusions hold beyond the
magic angle and for fully isolated defects. In summary, our results demonstrate
that the normal state of TBG and its moir\'e flat bands are extremely sensitive
to both the location and strength of non-magnetic impurities and vacancies,
which should have significant implications for any emergent ordered state.
We consider superconductivity in a system with $N$ Fermi surfaces, including
intraband and interband effective electron-electron interactions. The effective
interaction is described by an $N \times N$ matrix whose elements are assumed
to be constant in thin momentum shells around each Fermi surface, giving rise
to $s$-wave superconductivity. Starting with attractive intraband interactions
in all $N$ bands, we show that too strong interband interactions are
detrimental to sustaining $N$ nonzero components of the superconducting order
parameter. We find similar results in systems with repulsive intraband
interactions. The dimensionality reduction of the order-parameter space is
given by the number of nonpositive eigenvalues of the interaction matrix. Using
general models and models for superconducting transition metal dichalcogenides
and iron pnictides frequently employed in the literature, we show that
constraints must be imposed on the order parameter to ensure a lower bound on
the free energy and that subsequent higher-order expansions around the global
minimum are thermodynamically stable. We also demonstrate that similar
considerations are necessary for unconventional pairing symmetries.
Chern insulators, which are the lattice analogs of the quantum Hall states,
can potentially manifest high-temperature topological orders at zero magnetic
field to enable next-generation topological quantum devices. To date, integer
Chern insulators have been experimentally demonstrated in several systems at
zero magnetic field, but fractional Chern insulators have been reported only in
graphene-based systems under a finite magnetic field. The emergence of
semiconductor moir\'e materials, which support tunable topological flat bands,
opens a new opportunity to realize fractional Chern insulators. Here, we report
the observation of both integer and fractional Chern insulators at zero
magnetic field in small-angle twisted bilayer MoTe2 by combining the local
electronic compressibility and magneto-optical measurements. At hole filling
factor {\nu}=1 and 2/3, the system is incompressible and spontaneously breaks
time reversal symmetry. We determine the Chern number to be 1 and 2/3 for the
{\nu}=1 and {\nu}=2/3 gaps, respectively, from their dispersion in filling
factor with applied magnetic field using the Streda formula. We further
demonstrate electric-field-tuned topological phase transitions involving the
Chern insulators. Our findings pave the way for demonstration of quantized
fractional Hall conductance and anyonic excitation and braiding in
semiconductor moir\'e materials.
Employing the original, all-optical method, we quantify the magnetic
susceptibility of a two-dimensional electron gas (2DEG) confined in the
MoSe$_2$ monolayer in the range of low and moderate carrier densities. The
impact of electron-electron interactions on the 2DEG magnetic susceptibility is
found to be particularly strong in the limit of, studied in detail, low carrier
densities. Following the existing models, we derive the value of $g_0 = 2.5 \pm
0.4$ for the bare (in the absence of the interaction effects) $g$-factor of the
ground state electronic band in the MoSe$_2$ monolayer. The derived value of
this parameter is discussed in the context of estimations from other
experimental approaches. Surprisingly, the conclusions drawn differ from
theoretical ab-initio studies.
Quantum geometry - the geometry of electron Bloch wavefunctions - is central
to modern condensed matter physics. Due to the quantum nature, quantum geometry
has two parts, the real part quantum metric and the imaginary part Berry
curvature. The studies of Berry curvature have led to countless breakthroughs,
ranging from the quantum Hall effect in 2DEGs to the anomalous Hall effect
(AHE) in ferromagnets. However, in contrast to Berry curvature, the quantum
metric has rarely been explored. Here, we report a new nonlinear Hall effect
induced by quantum metric by interfacing even-layered MnBi2Te4 (a PT-symmetric
antiferromagnet (AFM)) with black phosphorus. This novel nonlinear Hall effect
switches direction upon reversing the AFM spins and exhibits distinct scaling
that suggests a non-dissipative nature. Like the AHE brought Berry curvature
under the spotlight, our results open the door to discovering quantum metric
responses. Moreover, we demonstrate that the AFM can harvest wireless
electromagnetic energy via the new nonlinear Hall effect, therefore enabling
intriguing applications that bridges nonlinear electronics with AFM
spintronics.
Novel critical phenomena beyond the Landau-Ginzburg-Wilson paradigm have been
long sought after. Among many candidate scenarios, the deconfined quantum
critical point (DQCP) constitutes the most fascinating one, and its lattice
model realization has been debated over the past two decades. Here we apply the
spherical Landau level regularization upon the exact (2+1)D SO(5) non-linear
sigma model with a topological term to study the potential DQCP therein.
Utilizing the state-of-the-art density matrix renormalization group method with
explicit $\text{SU(2)}_\text{spin}\times\text{U(1)}_\text{charge}$ symmetries,
accompanied by quantum Monte Carlo simulation, we accurately obtain the
comprehensive phase diagram of the model on a sphere. We find various novel
quantum phases, including a N\'eel state, a ferromagnet (FM), a valence bond
solid (VBS) state, a valley polarized (VP) state and quantum disordered phase
occupying extended area of the phase diagram. Our results show that two
different symmetry-breaking phases, i.e., the SO(2)-breaking VBS and the
SO(3)-breaking N\'eel states, are separated by either a weakly first-order
transition or the disordered region with a multicritical point in between, thus
opening up more interesting questions on this two-decade long debate on the
nature of DQCP.

Date of feed: Tue, 25 Jul 2023 00:30:00 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]+) **Fragmented superconductivity in the Hubbard model as solitons in Ginzburg-Landau theory. (arXiv:2307.11820v1 [cond-mat.str-el])**

Niccolò Baldelli, Benedikt Kloss, Matthew Fishman, Alexander Wietek

**First-principles Calculations of MoSeTe/WSeTe Bilayers: Stability, Phonons, Electronic Band Offsets, and Rashba Splitting. (arXiv:2307.11839v1 [cond-mat.mtrl-sci])**

Hamid Mehdipour, Peter Kratzer

**Higher-order Topological Point State. (arXiv:2307.11890v1 [cond-mat.mtrl-sci])**

Xiaoyin Li, Feng Liu

**Magnetism and topological property in icosahedral quasicrystal. (arXiv:2307.11898v1 [cond-mat.str-el])**

Shinji Watanabe

**Light-Driven Nanoscale Vectorial Currents. (arXiv:2307.11928v1 [cond-mat.mes-hall])**

Jacob Pettine, Prashant Padmanabhan, Teng Shi, Lauren Gingras, Luke McClintock, Chun-Chieh Chang, Kevin W. C. Kwock, Long Yuan, Yue Huang, John Nogan, Jon K. Baldwin, Peter Adel, Ronald Holzwarth, Abul K. Azad, Filip Ronning, Antoinette J. Taylor, Rohit P. Prasankumar, Shi-Zeng Lin, Hou-Tong Chen

**Minimal AC injection into Carbon Nanotubes. (arXiv:2307.11943v1 [cond-mat.mes-hall])**

Kota Fukuzawa, Takeo Kato, Thibaut Jonckheere, Jérôme Rech, Thierry Martin

**LCPOM: Precise Reconstruction of Polarized Optical Microscopy Images of Liquid Crystals. (arXiv:2307.11944v1 [cond-mat.soft])**

Chuqiao Chen, Viviana Palacio-Betancur, Sepideh Norouzi, Pablo F. Zubieta Rico, Monirosadat Sadati, Stuart J. Rowan, Juan J. de Pablo

**The mechanical response of fire ant rafts. (arXiv:2307.11966v1 [cond-mat.soft])**

Robert J. Wagner, Samuel Lamont, Zachary T. White, Franck J. Vernerey

**Imaging Josephson Vortices on Curved Junctions. (arXiv:2307.11970v1 [cond-mat.supr-con])**

Yuita Fujisawa, Anjana Krishnadas, Barnaby R.M. Smith, Markel Pardo-Almanza, Hoshu Hiyane, Yuki Nagai, Tadashi Machida, Yoshinori Okada

**Unconventional quantum criticality in a non-Hermitian extended Kitaev chain. (arXiv:2307.11996v1 [cond-mat.str-el])**

S Rahul, Nilanjan Roy, Ranjith R Kumar, Y R Kartik, Sujit Sarkar

**The Firs Room-Temperature Ambient-Pressure Superconductor. (arXiv:2307.12008v1 [cond-mat.supr-con])**

Sukbae Lee, Ji-Hoon Kim, Young-Wan Kwon

**Superconductor Pb_{10-x}Cu_x(PO_4)_6O showing levitation at room temperature and atmospheric pressure and mechanism. (arXiv:2307.12037v1 [cond-mat.supr-con])**

Sukbae Lee, Jihoon Kim, Hyun-Tak Kim, Sungyeon Im, SooMin An, Keun Ho Auh

**Quasi-bound Electron Pairs in Two-Dimensional Materials with a Mexican-Hat Dispersion. (arXiv:2307.12076v1 [cond-mat.str-el])**

Vladimir A. Sablikov, Aleksei A. Sukhanov

**Nonlinear Valley Hall Effect. (arXiv:2307.12088v1 [cond-mat.mes-hall])**

Kamal Das, Koushik Ghorai, Dimitrie Culcer, Amit Agarwal

**Ultrafast measurements of mode-specific deformation potentials of Bi$_2$Te$_3$ and Bi$_2$Se$_3$. (arXiv:2307.12132v1 [cond-mat.mtrl-sci])**

Yijing Huang, José D. Querales-Flores, Samuel W. Teitelbaum, Jiang Cao, Thomas Henighan, Hanzhe Liu, Mason Jiang, Gilberto De la Peña, Viktor Krapivin, Johann Haber, Takahiro Sato, Matthieu Chollet, Diling Zhu, Tetsuo Katayama, Robert Power, Meabh Allen, Costel R. Rotundu, Trevor P. Bailey, Ctirad Uher, Mariano Trigo, Patrick S. Kirchmann, Éamonn D. Murray, Zhi-Xun Shen, Ivana Savic, Stephen Fahy, Jonathan A. Sobota, David A. Reis

**Effects of Coulomb blockade on the charge transport through the topological states of finite armchair graphene nanoribbons and heterostructures. (arXiv:2307.12192v1 [cond-mat.mes-hall])**

David M T Kuo

**Observation of spin polarons in a frustrated moir\'e Hubbard system. (arXiv:2307.12205v1 [cond-mat.str-el])**

Zui Tao, Wenjin Zhao, Bowen Shen, Patrick Knüppel, Kenji Watanabe, Takashi Taniguchi, Jie Shan, Kin Fai Mak

**Green's Function Zeros in Fermi Surface Symmetric Mass Generation. (arXiv:2307.12223v1 [cond-mat.str-el])**

Da-Chuan Lu, Meng Zeng, Yi-Zhuang You

**The electronic structure of intertwined kagome, honeycomb, and triangular sublattices of the intermetallics MCo$_2$Al$_9$. (arXiv:2307.12269v1 [cond-mat.str-el])**

Chiara Bigi, Sahar Pakdel, Michał J. Winiarski, Pasquale Orgiani, Ivana Vobornik, Jun Fujii, Giorgio Rossi, Vincent Polewczyk, Phil D.C. King, Giancarlo Panaccione, Tomasz Klimczuk, Kristian Sommer Thygesen, Federico Mazzola

**Backscattering of topologically protected helical edge states by line defects. (arXiv:2307.12271v1 [cond-mat.mes-hall])**

Mohadese Karimi, Mohsen Amini, Morteza Soltani, Mozhgan Sadeghizadeh

**Spin-Peierls instability of the U(1) Dirac spin liquid. (arXiv:2307.12295v1 [cond-mat.str-el])**

Urban F. P. Seifert, Josef Willsher, Markus Drescher, Frank Pollmann, Johannes Knolle

**Active fractal networks with stochastic force monopoles and force dipoles unravel subdiffusion of chromosomal loci. (arXiv:2307.12310v1 [cond-mat.soft])**

Sadhana Singh, Rony Granek

**Quantum geometric-induced third-order nonlinear transport in antiferromagnetic topological insulator MnBi2Te4. (arXiv:2307.12313v1 [cond-mat.mtrl-sci])**

Hui Li, Chengping Zhang, Chengjie Zhou, Chen Ma, Xiao Lei, Hongtao He, Baikui Li, K. T. Law, Jiannong Wang

**Continuous unitary transformation approach to the Kondo-Majorana interplay. (arXiv:2307.12356v1 [cond-mat.mes-hall])**

Jan Baranski, Magdalena Baranska, Tomasz Zienkiewicz, Justyna Tomaszewska, Konrad Jerzy Kapcia

**Unravelling the Mechanics of Knitted Fabrics Through Hierarchical Geometric Representation. (arXiv:2307.12360v1 [cond-mat.soft])**

Xiaoxiao Ding, Vanessa Sanchez, Katia Bertoldi, Chris H. Rycroft

**Spin Space Group Theory and Unconventional Magnons in Collinear Magnets. (arXiv:2307.12366v1 [cond-mat.mtrl-sci])**

Xiaobing Chen, Jun Ren, Jiayu Li, Yuntian Liu, Qihang Liu

**Topological transition from nodal to nodeless Zeeman splitting in altermagnets. (arXiv:2307.12380v1 [cond-mat.mes-hall])**

Rafael M. Fernandes, Vanuildo S. de Carvalho, Turan Birol, Rodrigo G. Pereira

**Chiral topological whispering gallery modes formed by gyromagnetic photonic crystals. (arXiv:2307.12495v1 [physics.optics])**

Yongqi Chen, Nan Gao, Guodong Zhu, Yurui Fang

**Spin-dependent gain and loss in photonic quantum spin Hall systems. (arXiv:2307.12503v1 [cond-mat.mes-hall])**

Tian-Rui Liu, Kai Bai, Jia-Zheng Li, Liang Fang, Duanduan Wan, Meng Xiao

**Edge Theories for Anyon Condensation Phase Transitions. (arXiv:2307.12509v1 [cond-mat.str-el])**

David M. Long, Andrew C. Doherty

**Quantum Geometry and Landau Levels of Quadratic Band Crossing Points. (arXiv:2307.12528v1 [cond-mat.mes-hall])**

Junseo Jung, Hyeongmuk Lim, Bohm-Jung Yang

**Local topological order and boundary algebras. (arXiv:2307.12552v1 [math-ph])**

Corey Jones, Pieter Naaijkens, David Penneys, Daniel Wallick

**Adaptive active Brownian particles searching for targets of unknown positions. (arXiv:2307.12578v1 [cond-mat.soft])**

Harpreet Kaur, Thomas Franosch, Michele Caraglio

**Fate of localization in coupled free chain and disordered chain. (arXiv:2307.12631v1 [cond-mat.dis-nn])**

Xiaoshui Lin, Ming Gong

**Vibrational Entropic Stabilization of Layered Chalcogenides: From Ordered Vacancy Compounds to 2D Layers. (arXiv:2307.12640v1 [cond-mat.mtrl-sci])**

Roberto Prado-Rivera, Daniela Radu, Vincent H. Crespi, Yuanxi Wang

**Biaxial strain tuning of exciton energy and polarization in monolayer WS2. (arXiv:2307.12663v1 [cond-mat.mtrl-sci])**

G. Kourmoulakis, A. Michail, I. Paradisanos, X. Marie, M.M. Glazov, B. Jorissen, L. Covaci, E. Stratakis, K. Papagelis, J. Parthenios, G. Kioseoglou

**Harmonic to anharmonic tuning of moir\'e potential leading to unconventional Stark effect and giant dipolar repulsion in WS$_2$/WSe$_2$ heterobilayer. (arXiv:2307.12880v1 [cond-mat.mes-hall])**

Suman Chatterjee, Medha Dandu, Pushkar Dasika, Rabindra Biswas, Sarthak Das, Kenji Watanabe, Takashi Taniguchi, Varun Raghunathan, Kausik Majumdar

**Intruder in a two-dimensional granular system: statics and dynamics of force networks in an experimental system experiencing stick-slip dynamics. (arXiv:2307.12890v1 [cond-mat.soft])**

R. Basak, R. Kozlowski, L.A. Pugnaloni, M. Kramar, E.S. Socolar, C.M. Carlevaro, L. Kondic

**Quantum Duality in Electromagnetism and the Fine-Structure Constant. (arXiv:2307.12927v1 [hep-th])**

Clay Cordova, Kantaro Ohmori

**Competing mechanisms govern the thermal rectification behavior in semi-stochastic polycrystalline graphene with graded grain-density distribution. (arXiv:2307.12940v1 [cond-mat.mtrl-sci])**

Simanta Lahkar, Raghavan Ranganathan

**Collective epithelial migration is mediated by the unbinding of hexatic defects. (arXiv:2307.12956v1 [cond-mat.soft])**

Dimitrios Krommydas, Livio Nicola Carenza, Luca Giomi

**Coherent Phonons in Antimony: an Undergraduate Physical Chemistry Solid-State Ultrafast Laser Spectroscopy Experiment. (arXiv:2110.11423v2 [physics.ed-ph] UPDATED)**

Ilana J Porter, Michael W. Zuerch, Anne M. Baranger, Stephen R. Leone

**(3+1)D path integral state sums on curved U(1) bundles and U(1) anomalies of (2+1)D topological phases. (arXiv:2111.14827v2 [cond-mat.str-el] UPDATED)**

Ryohei Kobayashi, Maissam Barkeshli

**Electric-magnetic duality of $\mathbb{Z}_2$ symmetry enriched Abelian lattice gauge theory. (arXiv:2201.12361v2 [quant-ph] UPDATED)**

Zhian Jia, Dagomir Kaszlikowski, Sheng Tan

**Spin-texture topology in curved circuits driven by spin-orbit interactions. (arXiv:2209.11653v3 [cond-mat.mes-hall] UPDATED)**

Alberto Hijano, Eusebio J. Rodríguez, Dario Bercioux, Diego Frustaglia

**Visualizing and manipulating chiral interface states in a moir\'e quantum anomalous Hall insulator. (arXiv:2212.03380v2 [cond-mat.mes-hall] UPDATED)**

Canxun Zhang, Tiancong Zhu, Salman Kahn, Tomohiro Soejima, Kenji Watanabe, Takashi Taniguchi, Alex Zettl, Feng Wang, Michael P. Zaletel, Michael F. Crommie

**Polaronic and Mott insulating phase of layered magnetic vanadium trihalide VCl3. (arXiv:2301.06501v4 [cond-mat.mtrl-sci] UPDATED)**

Dario Mastrippolito, Luigi Camerano, Hanna Swiatek, Břetislav Šmíd, Tomasz Klimczuk, Luca Ottaviano, Gianni Profeta

**Demonstration of NV-detected $^{13}$C NMR at 4.2 T. (arXiv:2303.00740v2 [cond-mat.mes-hall] UPDATED)**

Yuhang Ren, Cooper Selco, Dylan Kawashiri, Michael Coumans, Benjamin Fortman, Louis S. Bouchard, Karoly Holczer, Susumu Takahashi

**Electrical control of spin and valley in spin-orbit coupled graphene multilayers. (arXiv:2303.04855v2 [cond-mat.str-el] UPDATED)**

Taige Wang, Marc Vila, Michael P. Zaletel, Shubhayu Chatterjee

**Realizing spin squeezing with Rydberg interactions in a programmable optical clock. (arXiv:2303.08078v2 [quant-ph] UPDATED)**

William J. Eckner, Nelson Darkwah Oppong, Alec Cao, Aaron W. Young, William R. Milner, John M. Robinson, Jun Ye, Adam M. Kaufman

**Revealing a 3D Fermi Surface Pocket and Electron-Hole Tunneling in UTe$_{2}$ with Quantum Oscillations. (arXiv:2303.09050v2 [cond-mat.str-el] UPDATED)**

Christopher Broyles, Zack Rehfuss, Hasan Siddiquee, Jiahui Althena Zhu, Kaiwen Zheng, Martin Nikolo, David Graf, John Singleton, Sheng Ran

**Non-Hermitian Chiral Skin Effect. (arXiv:2304.01422v2 [quant-ph] UPDATED)**

Xinran Ma, Kui Cao, Xiaoran Wang, Zheng Wei, Supeng Kou

**Defect-induced band restructuring and length scales in twisted bilayer graphene. (arXiv:2304.03018v2 [cond-mat.mes-hall] UPDATED)**

Lucas Baldo, Tomas Löthman, Patric Holmvall, Annica M. Black-Schaffer

**Constrained weak-coupling superconductivity in multiband superconductors. (arXiv:2304.13741v2 [cond-mat.supr-con] UPDATED)**

Niels Henrik Aase, Christian Svingen Johnsen, Asle Sudbø

**Integer and fractional Chern insulators in twisted bilayer MoTe2. (arXiv:2305.00973v3 [cond-mat.mes-hall] UPDATED)**

Yihang Zeng, Zhengchao Xia, Kaifei Kang, Jiacheng Zhu, Patrick Knüppel, Chirag Vaswani, Kenji Watanabe, Takashi Taniguchi, Kin Fai Mak, Jie Shan

**Enhancement of electron magnetic susceptibility due to many-body interactions in monolayer MoSe$_2$. (arXiv:2305.01501v3 [cond-mat.mes-hall] UPDATED)**

K. Oreszczuk, A. Rodek, M. Goryca, T. Kazimierczuk, M. Raczynski, J. Howarth, T. Taniguchi, K. Watanabe, M. Potemski, P. Kossacki

**Quantum metric nonlinear Hall effect in a topological antiferromagnetic heterostructure. (arXiv:2306.09575v2 [cond-mat.mes-hall] UPDATED)**

Anyuan Gao, Yu-Fei Liu, Jian-Xiang Qiu, Barun Ghosh, Thaís V. Trevisan, Yugo Onishi, Chaowei Hu, Tiema Qian, Hung-Ju Tien, Shao-Wen Chen, Mengqi Huang, Damien Bérubé, Houchen Li, Christian Tzschaschel, Thao Dinh, Zhe Sun, Sheng-Chin Ho, Shang-Wei Lien, Bahadur Singh, Kenji Watanabe, Takashi Taniguchi, David C. Bell, Hsin Lin, Tay-Rong Chang, Chunhui Rita Du, Arun Bansil, Liang Fu, Ni Ni, Peter P. Orth, Qiong Ma, Su-Yang Xu

**Phases of (2+1)D SO(5) non-linear sigma model with a topological term on a sphere: multicritical point and disorder phase. (arXiv:2307.05307v2 [cond-mat.str-el] UPDATED)**

Bin-Bin Chen, Xu Zhang, Yuxuan Wang, Kai Sun, Zi Yang Meng

Found 7 papers in prb Optical conductivity measurements may provide access to distinct signatures of Floquet electronic phases, described theoretically by their quasienergy band structures. In this paper we characterize experimental observables of the Floquet graphene antidot lattice (FGAL), which we introduced previousl… We demonstrate that the topological Hall effect (THE) in a $\mathrm{Pd}/{\mathrm{Tm}}_{3}{\mathrm{Fe}}_{5}{\mathrm{O}}_{12}$ (TmIG) bilayer can be delicately manipulated by ${\mathrm{H}}_{2}$ with a maximum $100%$ tunability in the reversible manner. This phenomenon originates from the variation of … Magnetic topological materials are a realization of topologically nontrivial electronic band structure with magnetic correlation effects; they offer novel opportunities in manipulating charge/spin transport as well as spin texture. In the search for emergent phenomena that are specific in this class… We have investigated a periodically driven Creutz ladder in the presence of two different driving protocols, namely, a sinusoidal drive and a $δ$ kick imparted to the ladder at regular intervals of time. Specifically, we have studied the topological properties corresponding to the trivial and the no… One-dimensional (1D) van der Waals (vdW) heterostructures have attracted great attention due to their excellent photoelectric properties which potentially serve as key components for next-generation optoelectronic devices. However, investigations on the photoelectric conversion properties in 1D vdW … Twisted layers of atomically thin two-dimensional materials support a broad range of quantum materials with engineered optical and transport properties. Transition metal dichalcogenides (TMDs) in the rhombohedral ($3R$, i.e., ${0}^{∘}$ twist) crystal phase have been the focus of significant research… We study two-terminal configurations in junctions between a topological superconducting wire with spin-orbit coupling and magnetic field, and an ordinary conductor with an embedded quantum dot. One of the signatures of the Majorana zero modes in the topological phase is a quantization of the zero-bi…

Date of feed: Tue, 25 Jul 2023 03:16:59 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]+) **Optical conductivity signatures of Floquet electronic phases**

Andrew Cupo, Joshuah T. Heath, Emilio Cobanera, James D. Whitfield, Chandrasekhar Ramanathan, and Lorenza Viola

Author(s): Andrew Cupo, Joshuah T. Heath, Emilio Cobanera, James D. Whitfield, Chandrasekhar Ramanathan, and Lorenza Viola

[Phys. Rev. B 108, 024308] Published Mon Jul 24, 2023

**Reversible manipulation of the topological Hall effect by hydrogen**

Lin Liu, Zhixiang Ye, Ruilin Zhang, Tao Lin, Mingxia Qiu, Shunpu Li, and Hongyu An

Author(s): Lin Liu, Zhixiang Ye, Ruilin Zhang, Tao Lin, Mingxia Qiu, Shunpu Li, and Hongyu An

[Phys. Rev. B 108, 024422] Published Mon Jul 24, 2023

**Quantum oscillations in the magnetic Weyl semimetal NdAlSi arising from strong Weyl fermion–$4f$ electron exchange interaction**

Jin-Feng Wang, Qing-Xin Dong, Yi-Fei Huang, Zhao-Sheng Wang, Zhao-Peng Guo, Zhi-Jun Wang, Zhi-An Ren, Gang Li, Pei-Jie Sun, Xi Dai, and Gen-Fu Chen

Author(s): Jin-Feng Wang, Qing-Xin Dong, Yi-Fei Huang, Zhao-Sheng Wang, Zhao-Peng Guo, Zhi-Jun Wang, Zhi-An Ren, Gang Li, Pei-Jie Sun, Xi Dai, and Gen-Fu Chen

[Phys. Rev. B 108, 024423] Published Mon Jul 24, 2023

**Topological properties of a periodically driven Creutz ladder**

Koustav Roy and Saurabh Basu

Author(s): Koustav Roy and Saurabh Basu

[Phys. Rev. B 108, 045415] Published Mon Jul 24, 2023

**Ultrafast interfacial charge transfer and superior photoelectric conversion properties in one-dimensional Janus-MoSSe/${\mathrm{WSe}}_{2}$ van der Waals heterostructures**

Biao Cai, Jianing Tan, Long Zhang, Degao Xu, Jiansheng Dong, and Gang Ouyang

Author(s): Biao Cai, Jianing Tan, Long Zhang, Degao Xu, Jiansheng Dong, and Gang Ouyang

[Phys. Rev. B 108, 045416] Published Mon Jul 24, 2023

**Electronic properties of rhombohedrally stacked bilayer $\mathrm{W}{\mathrm{Se}}_{2}$ obtained by chemical vapor deposition**

Aymen Mahmoudi, Meryem Bouaziz, Anis Chiout, Gaia Di Berardino, Nathan Ullberg, Geoffroy Kremer, Pavel Dudin, José Avila, Mathieu Silly, Vincent Derycke, Davide Romanin, Marco Pala, Iann C. Gerber, Julien Chaste, Fabrice Oehler, and Abdelkarim Ouerghi

Author(s): Aymen Mahmoudi, Meryem Bouaziz, Anis Chiout, Gaia Di Berardino, Nathan Ullberg, Geoffroy Kremer, Pavel Dudin, José Avila, Mathieu Silly, Vincent Derycke, Davide Romanin, Marco Pala, Iann C. Gerber, Julien Chaste, Fabrice Oehler, and Abdelkarim Ouerghi

[Phys. Rev. B 108, 045417] Published Mon Jul 24, 2023

**Transport features of a topological superconducting nanowire with a quantum dot: Conductance and noise**

Leonel Gruñeiro, Miguel Alvarado, Alfredo Levy Yeyati, and Liliana Arrachea

Author(s): Leonel Gruñeiro, Miguel Alvarado, Alfredo Levy Yeyati, and Liliana Arrachea

[Phys. Rev. B 108, 045418] Published Mon Jul 24, 2023

Found 1 papers in prl We report a search for light dark matter produced through the cascading decay of $η$ mesons, which are created as a result of inelastic collisions between cosmic rays and Earth’s atmosphere. We introduce a new and general framework, publicly accessible, designed to address boosted dark matter specif…

Date of feed: Tue, 25 Jul 2023 03:16:58 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]+) **Search for Light Dark Matter from the Atmosphere in PandaX-4T**

Xuyang Ning *et al.* (PandaX Collaboration)

Author(s): Xuyang Ning *et al.* (PandaX Collaboration)

[Phys. Rev. Lett. 131, 041001] Published Mon Jul 24, 2023

Found 1 papers in pr_res We develop a topological classification of non-Hermitian effective Hamiltonians that depend on momentum and frequency. Such effective Hamiltonians are in one-to-one correspondence to single-particle Green's functions of systems that satisfy translational invariance in space and time but may be inter…

Date of feed: Tue, 25 Jul 2023 03:16:59 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]+) **Topological classification of non-Hermitian Hamiltonians with frequency dependence**

Maximilian Kotz and Carsten Timm

Author(s): Maximilian Kotz and Carsten Timm

[Phys. Rev. Research 5, 033043] Published Mon Jul 24, 2023