Found 57 papers in cond-mat A fundamental question in complex systems is how to relate interactions
between individual components ("microscopic description") to the global
properties of the system ("macroscopic description"). Another fundamental
question is whether such a macroscopic description exists at all and how well
it describes the large-scale properties. Here, we address these questions using
as a canonical example of a self-organizing complex system - the collective
motion of desert locusts. One of the world's most devastating insect plagues
begins when flightless juvenile locusts form "marching bands". Moving through
semiarid habitats in the search for food, these bands display remarkable
coordinated motion. We investigated how well physical models can describe the
flow of locusts within a band. For this, we filmed locusts within marching
bands during an outbreak in Kenya and automatically tracked all individuals
passing through the camera frame. We first analysed the spatial topology of
nearest neighbors and found individuals to be isotropically distributed.
Despite this apparent randomness, a local order was observed in regions of high
density with a clear second neighbor peak in the radial distribution function,
akin to an ordered fluid. Furthermore, reconstructing individual locust
trajectories revealed a highly-aligned movement, consistent with the
one-dimensional version of the Toner-Tu equations, which are a generalization
of the Navier-Stokes equations for fluids, used to describe the equivalent
macroscopic fluid properties of active particles. Using this effective Toner-Tu
equation, which relates the gradient of the pressure to the acceleration, we
show that the effective "pressure" of locusts increases as a linear function of
density in segments with highest polarization. Our study thus demonstrates an
effective hydrodynamic description of flow dynamics in plague locust swarms.
Helical twisted trilayer graphene exhibits zero-energy flat bands with large
degeneracy in the chiral limit. The flat bands emerge at a discrete set of
magic twist angles and feature properties intrinsically distinct from those
realized in twisted bilayer graphene. Their degeneracy and the associated band
Chern numbers depend on the parity of the magic angles. Two degenerate flat
bands with Chern numbers $C_A=2$ and $C_B=-1$ arise at odd magic angles,
whereas even magic angles display four flat bands, with Chern number
$C_{A/B}=\pm1$, together with a Dirac cone crossing at zero energy. All bands
are sublattice polarized. We demonstrate the structure behind these flat bands
and obtain analytical expressions for the wavefunctions in all cases. Each
magic angle is identified with the vanishing of a zero-mode wavefunction at
high-symmetry position and momentum. The whole analytical structure results
from whether the vanishing is linear or quadratic for the, respectively, odd
and even magic angle. The $C_{3z}$ and $C_{2y}T$ symmetries are shown to play a
key role in establishing the flat bands. In contrast, the particle-hole
symmetry is not essential, except from gapping out the crossing Dirac cone at
even magic angles.
The integer quantum anomalous Hall (QAH) effect is a lattice analog of the
quantum Hall effect at zero magnetic field. This striking transport phenomenon
occurs in electronic systems with topologically nontrivial bands and
spontaneous time-reversal symmetry breaking. Discovery of its putative
fractional counterpart in the presence of strong electron correlations, i.e.,
the fractional quantum anomalous Hall (FQAH) effect, would open a new chapter
in condensed matter physics. Here, we report the direct observation of both
integer and fractional QAH effects in electrical measurements on twisted
bilayer MoTe$_2$. At zero magnetic field, near filling factor $\nu = -1$ (one
hole per moir\'e unit cell) we see an extended integer QAH plateau in the Hall
resistance $R_\text{xy}$ that is quantized to $h/e^2 \pm 0.1 \%$ while the
longitudinal resistance $R_\text{xx}$ vanishes. Remarkably, at $\nu=-2/3$ and
$-3/5$ we see plateau features in $R_\text{xy}$ at $3h/2e^2 \pm 1\%$ and
$5h/3e^2 \pm 3\%$, respectively, while $R_\text{xx}$ remains small. All these
features shift linearly in an applied magnetic field with slopes matching the
corresponding Chern numbers $-1$, $-2/3$, and $-3/5$, precisely as expected for
integer and fractional QAH states. In addition, at zero magnetic field,
$R_\text{xy}$ is approximately $2h/e^2$ near half filling ($\nu = -1/2$) and
varies linearly as $\nu$ is tuned. This behavior resembles that of the
composite Fermi liquid in the half-filled lowest Landau level of a
two-dimensional electron gas at high magnetic field. Direct observation of the
FQAH and associated effects paves the way for researching charge
fractionalization and anyonic statistics at zero magnetic field.
The nonlinear wave propagation in large extra spatial dimensions (on and
above $d=2$) is investigated in the context of nonlinear electrodynamics
theories that depends exclusively on the invariant $\mathcal{F}$. In this vein,
we consider propagating waves under the influence of external uniform electric
and magnetic fields. Features related to the blackbody radiation in the
presence of a background constant electric field such as the generalization of
the spectral energy density distribution and the Stefan-Boltzmann law are
obtained. Interestingly enough, anisotropic contributions to the frequency
spectrum appear in connection to the nonlinearity of the electromagnetic field.
In addition, the long wavelength regime and the Wien's displacement law in this
situation are studied. The corresponding thermodynamics quantities at thermal
equilibrium, such as energy, pressure, entropy and heat capacity densities are
contemplated as well.
Screened plasmon properties of graphene near a perfect electric conductor are
investigated using classical electrodynamics and a linearized hydrodynamic
model that includes Fermi correction. A general expression for the dispersion
relation of the mentioned screened plasmonic waves is given and illustrated
graphically. The result indicates that for realistic wavenumbers, the
dispersion relation of plasmonic waves of isolated graphene is almost
unaffected by the Fermi correction, while this correction is an important
factor for the screened plasmons of graphene near a perfect electric conductor,
where it increases the frequency of surface waves. The results show that near
the graphene neutrality point, the surface wave has a linear dispersion with a
universal speed close to $v_{\mathrm{F}}/\sqrt{2}$. Such linear dispersion for
surface waves (also known as energy waves) appears to be a common occurrence
when a splitting of plasma frequencies occurs, e.g. in the electron-hole plasma
of graphene [W. Zhao \textit{et al}., Nature \textbf{614}, 688 (2023)].
Furthermore, analytical expressions for the energy parameters (the power flow,
energy density, and energy velocity) of screened plasmons of the system are
derived. Also, the analytical expressions are derived and analyzed for the
damping function and surface plasmon and electromagnetic field strength
functions of surface waves of the system with small intrinsic damping.
The electronic structure of Nickel dichalcogenides, NiS$_2$ and NiSe$_2$, in
monolayer form, is studied employing first-principles methods. We assess the
importance of band ordering, covalency and Coulomb interactions in the ground
state of these systems. Hybrid functional results are compared with standard
functionals and also with Hubbard-corrected functionals to systematically
address the role of electronic interactions and localization. We found that
mean-field correlation realized by intersite Hubbard interactions are directly
linked to the magnitude of the energy band gap, giving compelling evidence for
the presence of a charge transfer insulating phase in these materials.
Atomically thin transition metal dichalcogenides can exhibit markedly
different electronic properties compared to their bulk counterparts. In the
case of NbSe$_2$, the question of whether its charge density wave (CDW) phase
is enhanced in the monolayer limit has been the subject of intense debate,
primarily due to the difficulty of decoupling this order from its environment.
Here, we address this challenge by using a misfit crystal that comprises
NbSe$_2$ monolayers separated by SnSe rock-salt spacers, a structure that
allows us to investigate a monolayer crystal embedded in a bulk matrix. We
establish an effective monolayer electronic behavior of the misfit crystal by
studying its transport properties and visualizing its electronic structure by
angle-resolved photoemission measurements. We then investigate the emergence of
the CDW by tracking the temperature dependence of its collective modes. Our
findings reveal a nearly sixfold enhancement in the CDW transition temperature,
providing compelling evidence for the profound impact of dimensionality on
charge order formation in NbSe$_2$.
In recent experimental and theoretical studies of graphene, disorder
scattering processes have been suggested to play an important role in its
electronic and transport properties. In the preceding paper, it has been shown
that the nonperturbative momentum-space Lanczos method is able to accurately
describe all the multiple impurity scattering events and account for the
quasiparticle and transport properties of disordered monolayer graphene. In the
present study, we expand the range of applicability of this recursive method by
numerically investigating the quasiparticle and transport properties of
Bernal-stacked bilayer graphene in the presence of scalar Anderson disorder.
The results are further compared with the findings of the same system using a
self-consistent Born approximation, as well as the central findings in the
preceding paper for monolayer graphene. It is found that in both systems,
proper inclusions of all the scattering events are needed in order to reliably
capture the role of disorder via multiple impurity scattering. In particular,
the quasiparticle residue is shown to decrease sharply near the charge
neutrality point, suggesting that the system is either a marginal Fermi liquid
or a non-Fermi liquid. Furthermore, we reveal the dependences of the transport
properties of disordered bilayer graphene on the carrier density and
temperature, and explore the role of interlayer scattering at varying
strengths. Our findings help to provide some new angles into the quasiparticle
and transport properties of disordered bilayer graphene.
Static friction induced by moir\'e superstructure in twisted incommensurate
finite layered material interfaces reveals unique double periodicity and lack
of scaling with contact size. The underlying mechanism involves compensation of
incomplete moir\'e tiles at the rim of rigid polygonal graphene flakes sliding
atop fixed graphene or h-BN substrates. The scaling of friction (or lack
thereof) with contact size is found to strongly depend on the shape of the
slider and the relative orientation between its edges and the emerging
superstructure, partially rationalizing scattered experimental data. With
careful consideration of the flake edge orientation, twist angle, and sliding
direction along the substrate, one should therefore be able to achieve
large-scale superlubricity via shape tailoring.
Semiconducting transition-metal dichalcogenides (TMDs) exhibit high mobility,
strong spin-orbit coupling, and large effective masses, which simultaneously
leads to a rich wealth of Landau quantizations and inherently strong electronic
interactions. However, in spite of their extensively explored Landau levels
(LL) structure, probing electron correlations in the fractionally filled LL
regime has not been possible due to the difficulty of reaching the quantum
limit. Here, we report evidence for fractional quantum Hall (FQH) states at
filling fractions 4/5 and 2/5 in the lowest LL of bilayer MoS$_{2}$, manifested
in fractionally quantized transverse conductance plateaus accompanied by
longitudinal resistance minima. We further show that the observed FQH states
result from and sensitively depend on the dielectric and gate screening of the
Coulomb interactions. Our findings establish a new FQH experimental platform
which are a scarce resource: it is tunable by Coulomb-screening engineering and
as such, is the missing link between atomically thin graphene and
semiconducting quantum wells.
Different dynamical states ranging from coherent, incoherent to chimera,
multichimera, and related transitions are addressed in a globally coupled
nonlinear continuum chemical oscillator system by implementing a modified
complex Ginzburg-Landau equation. Besides dynamical identifications of observed
states using standard qualitative metrics, we systematically acquire
nonequilibrium thermodynamic characterizations of these states obtained via
coupling parameters. The nonconservative work profiles in collective dynamics
qualitatively reflect the time-integrated concentration of the activator, and
the majority of the nonconservative work contributes to the entropy production
over the spatial dimension. It is illustrated that the evolution of spatial
entropy production and semigrand Gibbs free energy profiles associated with
each state are connected yet completely out of phase, and these thermodynamic
signatures are extensively elaborated to shed light on the exclusiveness and
similarities of these states. Moreover, a relationship between the proper
nonequilibrium thermodynamic potential and the variance of activator
concentration is established by exhibiting both quantitative and qualitative
similarities between a Fano factor-like entity, derived from the activator
concentration, and the Kullback-Leibler divergence associated with the
transition from a nonequilibrium homogeneous state to an inhomogeneous state.
Quantifying the thermodynamic costs for collective dynamical states would aid
in efficiently controlling, manipulating, and sustaining such states to explore
the real-world relevance and applications of these states.
There has been an increasing research focus on quantum algorithms for
condensed matter systems recently, particularly on calculating energy band
structures. Here, we propose a quantum algorithm, the powered full quantum
eigensolver(P-FQE), by using the exponentiation of operators of the full
quantum eigensolver(FQE). This leads to an exponential increase in the success
probability of measuring the target state in certain circumstances where the
number of generating elements involved in the exponentiation of operators
exhibit a log polynomial dependence on the number of orbitals. Furthermore, we
conduct numerical calculations for band structure determination of the twisted
double-layer graphene. We experimentally demonstrate the feasibility and
robustness of the P-FQE algorithm using superconducting quantum computers for
graphene and Weyl semimetal. One significant advantage of our algorithm is its
ability to reduce the requirements of extremely high-performance hardware,
making it more suitable for energy spectra determination on noisy
intermediate-scale quantum (NISQ) devices.
We explain the appearance of magic angle flat bands and fractional Chern
insulators in twisted K-valley homobilayer transition metal dichalcogenides by
mapping their continuum model to a Landau level problem. Our approach relies on
an adiabatic approximation for the quantum mechanics of valence band holes in a
layer-pseudospin field that is valid for sufficiently small twist angles and on
a lowest Landau level approximation that is valid for sufficiently large twist
angles. It simply explains why the quantum geometry of the lowest moir\'e
miniband is close to ideal at the flat-band twist angle, predicts that flat
bands occur only when the valley-dependent moir\'e potential is sufficiently
strong compared to the interlayer tunneling amplitude, and provides a powerful
starting point for the study of interactions.
Incorporating plasmonic metal nanostructures into the semiconductor compounds
in the form of core-shell offers a new route to improving the performance of
photodetectors. Herein, we have reported the development of a high-performance
photodetector based on Cu2NiSnS4 (CNTS) nanocrystals (NCs) and Au/CNTS
core-shell structures (complex or others, instead NC), for the first time, as a
proof-of-concept experiment using the colloidal hot-injection method. The
photoactive Au/CNTS core-shell NCs exhibit enhanced optical absorption, carrier
extraction efficiency, and improved photo-sensing performance. It is depicted
that using this Au/CNTS core-shell/graphene-based photodetector, there is a
significant increment in optoelectronic responses compared to using a pristine
CNTS/graphene-based photodetector. The maximum responsivity, detectivity, and
external quantum efficiency (EQE) of 1.2 $\times 10^{3}$ AW$^{-1}$, 6.2$\times
10^{11}$ Jones, and 3.8$\times 10^{5}$ \% were measured at an illumination
power density of 318.5 $\mu$Wcm-2. Importantly, this enhanced optoelectronic
performance is mainly due to the plasmonic-induced resonance energy transfer
(PIRET) effect of core Au; carrier density is significantly increased between
the Au core and CNTS shell. Further, the device using Au/CNTS exhibits a fast
response/recovery time of 2.58/11.14 sec and excellent operational reliability.
These results enlighten a new era in the fabrication and development of
plasmonic core-shell nanostructures-based visible photo-sensing devices for
imaging applications.
Topological magnon insulators (TMI) are ordered magnets supporting chiral
edge magnon excitations. These edge states are envisioned to serve as
topologically protected information channels in low-loss magnonic devices. The
standard description of TMI is based on linear spin-wave theory (LSWT), which
approximates magnons as free non-interacting particles. However, magnon
excitations of TMI are genuinely interacting even at zero temperature, calling
into question descriptions based on LSWT alone. Here we perform a detailed
non-linear spin-wave analysis to investigate the stability of chiral edge
magnons. We identify three general breakdown mechanisms: (1) The edge magnon
couples to itself, generating a finite lifetime that can be large enough to
lead to a spectral annihilation of the chiral state; (2) The edge magnon
hybridizes with the extended bulk magnons and, as a consequence, delocalizes
away from the edge; (3) Due to a bulk-magnon mediated edge-to-edge coupling,
the chiral magnons at opposite edges hybridize. We argue that, in general,
these breakdown mechanisms may invalidate predictions based on LSWT and violate
the notion of topological protection. We discuss strategies how the breakdown
of chiral edge magnons can be avoided, e.g. via the application of large
magnetic fields. Our results highlight a challenge for the realization of
chiral edge states in TMI and in other bosonic topological systems without
particle number conservation.
We demonstrate terahertz chiral metamaterial cavities that break
time-reversal symmetry by coupling the degenerate linearly polarized modes of
two orthogonal sets of nano-antenna arrays using the inter-Landau level
transition of a two-dimensional electron gas in a perpendicular magnetic field,
realizing normalized light-matter coupling rates up to
$\Omega_R/\omega_{\mathrm{cav}} = 0.78$. The deep sub-wavelength confinement
and gap of the nano-antennas means that the ultra-strong coupling regime can be
reached even with a very small number of carriers, making it viable to be used
with a variety of 2D materials, including graphene. In addition it possesses a
non-degenerate chiral ground state that can be used to study the effect of
circularly polarized electromagnetic quantum fluctuations by means of
weakly-perturbing magneto-transport measurements.
Transition metal dichalcogenide (TMDC) moir\'e superlattices, owing to the
moir\'e flatbands and strong correlation, can host periodic electron crystals
and fascinating correlated physics. The TMDC heterojunctions in the type-II
alignment also enable long-lived interlayer excitons that are promising for
correlated bosonic states, while the interaction is dictated by the asymmetry
of the heterojunction. Here we demonstrate a new excitonic state, quadrupolar
exciton, in a symmetric WSe2-WS2-WSe2 trilayer moir\'e superlattice. The
quadrupolar excitons exhibit a quadratic dependence on the electric field,
distinctively different from the linear Stark shift of the dipolar excitons in
heterobilayers. This quadrupolar exciton stems from the hybridization of WSe2
valence moir\'e flatbands. The same mechanism also gives rise to an interlayer
Mott insulator state, in which the two WSe2 layers share one hole laterally
confined in one moir\'e unit cell. In contrast, the hole occupation probability
in each layer can be continuously tuned via an out-of-plane electric field,
reaching 100% in the top or bottom WSe2 under a large electric field,
accompanying the transition from quadrupolar excitons to dipolar excitons. Our
work demonstrates a trilayer moir\'e system as a new exciting playground for
realizing novel correlated states and engineering quantum phase transitions.
Hydrogen is a crucial source of green energy and has been extensively studied
for its potential usage in fuel cells. The advent of two-dimensional crystals
(2DCs) has taken hydrogen research to new heights, enabling it to tunnel
through layers of 2DCs or be transported within voids between the layers, as
demonstrated in recent experiments by Geim's group. In this study, we
investigate how the composition and stacking of transition-metal dichalcogenide
(TMDC) layers influence the transport and self-diffusion coefficients (D) of
hydrogen atoms using well-tempered metadynamics simulations. Our findings show
that modifying either the transition metal or the chalcogen atoms significantly
affects the free energy barriers (Delta F) and, consequently, the
self-diffusion of hydrogen atoms between the 2DC layers. In the Hh polytype (2H
stacking), MoSe2 exhibits the lowest Delta F, while WS2 has the highest,
resulting in the largest D for the former system. Additionally, hydrogen atoms
inside the RhM (or 3R) polytype encounter more than twice lower energy barriers
and, thus, much higher diffusivity compared to those within the most stable Hh
stacking. These findings are particularly significant when investigating
twisted layers or homo- or heterostructures, as different stacking areas may
dominate over others, potentially leading to directional transport and
interesting materials for ion or atom sieving.
Large spin-orbit coupling, kagome lattice, nontrivial topological band
structure with inverted bands anti-crossings, and Weyl nodes are essential
ingredients, ideally required to obtain maximal anomalous Hall effect (AHE) are
simultaneously present in Co$_3$Sn$_2$S$_2$. It is a leading platform to show
large intrinsic anomalous Hall conductivity (AHC) and giant anomalous Hall
angle (AHA) simultaneously at low fields. The giant AHE in Co$_3$Sn$_2$S$_2$ is
robust against small-scale doping-related chemical potential changes. In this
work, we unveil a selective and co-chemical doping route to maximize AHEs in
Co$_3$Sn$_2$S$_2$. To begin with, in Co$_3$Sn$_{2-x}$In$_x$S$_2$, we brought
the chemical potential at the hotspot of Berry curvature along with a maximum
of asymmetric impurity scattering in high mobility region. As a result at
x=0.05, we found a significant enhancement of AHA (95%) and AHC (190%) from the
synergistic enhancement of extrinsic and intrinsic mechanisms from modified
Berry curvature of gaped nodal lines. Later, with anticipation of further
improvements in AHE, we grew hole-co-doped
Co$_{3-y}$Fe$_y$Sn$_{2-x}$In$_x$S$_2$ crystals, where we found rather a
suppression of AHEs. The role of dopants in giving extrinsic effects or band
broadening can be better understood when chemical potential does not change
after doping. By simultaneous and equal co-doping with electrons and holes in
Co$_{3-y-z}$Fe$_y$Ni$_z$Sn$_2$S$_2$, we kept the chemical potential unchanged.
Henceforth, we found a significant enhancement in intrinsic AHC $\sim$116% due
to the disorder broadenings in kagome bands
Realization of non-Abelian anyons in topological phases is a crucial step
toward topological quantum computation. We propose a scheme to realize a
non-Abelian quantum spin liquid (QSL) phase in a three-component Bose gas with
contact interaction on optical Kagome lattices. In the strong coupling regime,
the system is described by an effective spin-1 model with two- and three-body
interactions between neighboring spins. By mapping out the phase diagram via
variational Monte Carlo method, we find a non-Abelian chiral spin liquid phase
in which the Ising-type anyons obey non-Abelian braiding statistics. The
gapless chiral edge states can be detected by measuring the spin-spin
correlation from atomic population. Furthermore, an interesting Z2 QSL phase is
observed exhibiting both topological order and lattice symmetry breaking order.
Our scheme can be implemented in cold quantum gases of bosonic atoms.
Starting from Halperin multilayer systems we develop a hierarchical scheme
that generates, bosonic and fermionic, single-layer quantum Hall states (or
vacua) of arbitrary filling factor. Our scheme allows for the insertion of
quasiparticle excitations with either Abelian or non-Abelian statistics and
quantum numbers that depend on the nature of the original vacuum. Most
importantly, it reveals a fusion mechanism for quasielectrons and
magnetoexcitons that generalizes ideas about particle fractionalization
introduced in Commun. Phys. 5, 171 (2022) for the case of Laughlin fluids. In
addition, in the second quantization representation, we uncover the inherent
topological quantum order characterizing these vacua. In particular, we
illustrate the methodology by constructing generalized composite (generalized
Read) operators for the non-Abelian Pfaffian and Hafnian quantum fluid states.
Given a finite set of two-dimensional tile types, the field concerned with
covering the plane with tiles of these types only has a long history, having
enjoyed great prominence in the last six to seven decades, not only as a topic
of recreational mathematics but mainly as a topic of scientific interest. Much
of this interest has revolved around fundamental geometrical problems such as
minimizing the variety of tile types to be used, and also around important
applications in areas such as crystallography and others concerned with various
atomic- and molecular-scale phenomena. All applications are of course confined
to finite regions, but in many cases they refer back directly to progress in
tiling the whole plane. Tilings of bounded regions of the plane have also been
actively studied, but in general the additional complications imposed by the
boundary conditions tend to constrain progress to mostly indirect results, such
as recurrence relations. Here we study the tiling of rectangular regions of the
plane by squares, dominoes, and straight tetraminoes. For this set of tile
types, not even recurrence relations seem to be available. Our approach is to
seek to characterize this system through some of the fundamental quantities of
statistical physics. We do this on two parallel tracks, one fully analytical
for a special case, the other based on the Wang-Landau method for state-density
estimation. Given a simple Hamiltonian based solely on tile contacts, we have
found either approach to lead to illuminating depictions of entropy,
temperature, and above all phase separation. The notion of phase separation, in
this context, refers to keeping track of how many tiles of each type are used
in each of the many possibilities. We have found that this helps bind together
different aspects of the system in question and conjecture that future
applications will benefit from the possibilities it affords.
A driven quantum system can experience Landau-Zener-Stueckelberg-Majorana
(LZSM) transitions between its states, when the respective energy levels
quasi-cross. If this quasicrossing is passed repeatedly under periodic driving,
the trajectories can interfere either constructively or destructively. In the
latter case, known as coherent destruction of tunneling, the transition between
the energy states is suppressed. Even for a double-passage case, the
accumulated phase difference (also referred to as the Stueckelberg phase) can
lead to destructive interference, resulting in no transition. In this paper we
discuss a similar process for a single-passage dynamics. We study the LZSM
single-passage problem starting from a superposition state. The phase
difference of this initial state results in interference. When this is
destructive, resulting in a zero transition probability, such situation can be
called single-passage coherent destruction of tunneling. When the phase is
chosen so that the occupation probabilities do not change after the transition,
this can be called occupation conservation and this is analogous to the problem
of transitionless driving. We demonstrate how varying the system parameters
(driving velocity, initial phase, initial detuning) can be used for quantum
control.
The presence of electron correlations in a system with topological order can
lead to exotic ground states. Considering single crystals of LaAgSb2 which has
a square net crystal structure, one finds multiple charge density wave
transitions (CDW) as the temperature is lowered. We find large planar Hall
(PHE) signals in the CDW phase, which are still finite in the high temperature
phase though they change sign. Optimising the structure within first-principles
calculations, one finds an unusual chiral metallic phase. This is because as
the temperature is lowered, the separation between the Ag/Sb atoms on different
layers decreases, leading to stronger repulsions between electrons associated
with atoms on different layers. This leads to successive layers sliding with
respect to each other, thereby stabilising a chiral structure in which
inversion symmetry is also broken. The large Berry curvature associated with
the low-temperature structure explains the low temperature PHE. At high
temperature, the PHE arises from the changes induced in the anisotropic Dirac
cone in presence a magnetic field. Our work represents a route towards
detecting and understanding the mechanism in a correlation driven topological
transition through electron transport measurements, complemented by ab-initio
electronic structure calculations.
We report the single crystal growth and characterization of EuIn$_2$, a
magnetic topological semimetal candidate according to our density functional
theory (DFT) calculations. We present results from electrical resistance,
magnetization, M\"ossbauer spectroscopy, and X-ray resonant magnetic scattering
(XRMS) measurements. We observe three magnetic transitions at
$T_{\text{N}1}\sim 14.2~$K, $T_{\text{N}2}\sim12.8~$K and $T_{\text{N}3}\sim
11~$K, signatures of which are consistently seen in anisotropic temperature
dependent magnetic susceptibility and electrical resistance data. M\"ossbauer
spectroscopy measurements on ground crystals suggest an incommensurate
sinusoidally modulated magnetic structure below the transition at
$T_{\text{N}1}\sim 14~$K, followed by the appearance of higher harmonics in the
modulation on further cooling roughly below $T_{\text{N}2}\sim13~$K, before the
moment distribution squaring up below the lowest transition around
$T_{\text{N}3}\sim 11~$K. XRMS measurements showed the appearance of magnetic
Bragg peaks below $T_{\text{N}1}\sim14~$K, with a propagation vector of
$\bm{\tau}$ $=(\tau_h,\bar{\tau}_h,0)$, with $\tau_h$varying with temperature,
and showing a jump at $T_{\text{N}3}\sim11$~K. The temperature dependence of
$\tau_h$ between $\sim11$~K and $14$~K shows incommensurate values consistent
with the M\"{o}ssbauer data. XRMS data indicate that $\tau_h$ remains
incommensurate at low temperatures and locks into $\tau_h=0.3443(1)$.
Effects of a bias electric current have been theoretically investigated in a
spin-triplet superconducting ring in a magnetic field. Based on the
Ginzburg-Landau theory, we show that the bias current can stabilize a
half-quantum-flux (HQF) state via couplings to the Zeeman field and the
dipole-type spin-orbit interaction, the latter becoming active when the field
is tilted from the ring axis. The emergence of the HQF state is reflected as a
field-induced half-quantum-shift in the Little-Parks (LP) oscillation in the
critical current. Possible relevance to recent LP experiments is also
discussed.
We present analytic expressions for the density of states and its consistent
derivation for the two-dimensional Qi-Wu-Zhang (QWZ) Hamiltonian, a generic
model for the Chern topological insulators of class A. This density of states
is expressed in terms of elliptical integrals. We discuss and plot special
cases of the dispersion relations and the corresponding densities of states.
Spectral moments are also presented. The exact formulae ought to be useful in
determining physical properties of the non-interacting Chern insulators and
within the dynamical mean-field theory for interacting fermions with the QWZ
Hamiltonian in the non-interacting limit.
Two-dimensional (2D) ferrovalley semiconductor (FVSC) with spontaneous valley
polarization offers an exciting material platform for probing Berry phase
physics. How FVSC can be incorporated in valleytronic device applications,
however, remain an open question. Here we generalize the concept of
metal/semiconductor (MS) contact into the realm of valleytronics. We propose
the concept of half-valley Ohmic contact in FVSC/graphene heterostructures
where the two valleys of FVSC separately forms Ohmic and Schottky contacts with
the those of graphene, thus allowing current to be valley-selectively injected
through the `Ohmic' valley while being blocked in the `Schottky' valley. We
develop a theory of \emph{contact-limited valley-contrasting current injection}
and demonstrate such transport mechanism can produce gate-tunable
valley-polarized injection current across a FVSC/graphene contact. Using
RuCl$_2$/graphene heterostructure as a proof of concept, we illustrate a device
concept of valleytronic barristor in whcih high valley polarization efficiency,
accompanied by a sizable current on/off ratio, can be achieved under
experimentally achievable electrostatic gating conditions. These findings
uncover contact-limited valley-contrasting current injection as an efficient
mechanism for valley polarization manipulation, and reveals the potential of
valleytronic MS contact as a functional building block of valleytronic device
technology.
Periodic spatial modulations of the superfluid density, or pair density
waves, have now been widely detected in unconventional superconductors, either
as the primary or the secondary states accompanying charge density waves.
Understanding how these density waves emerge, or conversely get suppressed by
external parameters, provides an important insight into their nature. Here we
use spectroscopic imaging scanning tunneling microscopy to study the evolution
of density waves in the heavy fermion spin-triplet superconductor UTe2 as a
function of temperature and magnetic field. We discover that charge
modulations, composed of three different wave vectors gradually weaken but
persist to a surprisingly high temperature T_CDW ~ 10-12 K. By tracking the
local amplitude of modulations, we find that these modulations become spatially
inhomogeneous, and form patches that shrink in size with higher temperature or
with applied magnetic field. Interestingly, one of the density wave vectors
along the mirror symmetry has a slightly different temperature onset, thus
revealing an unexpected decoupling of the three-component CDW state.
Importantly, T_CDW determined from our work matches closely to the temperature
scale believed to be related to magnetic fluctuations, providing the first
possible connection between density waves observed by surface probes and bulk
measurements. Combined with magnetic field sensitivity of the modulations, this
could point towards an important role of spin fluctuations or short-range
magnetic order in the formation of the primary charge density wave.
Recent density-functional theory (DFT) calculations on copper-doped lead
apatite $\text{Pb}_9\text{Cu}(\text{PO}_4)_6\text{O}$ indicated various
interesting band structure properties in the close vicinity to the Fermi
surface including symmetry-enforced band crossings, narrow bands, and van-Hove
singularities. These studies assume a regular arrangement of the dopant, such
that the space group (SG) 176 (P6$\text{}_3$/m) is reduced to SG 143 (P3). We
construct tight-binding models for this space group with two and four bands. A
first analysis of these models show excellent agreement with the key features
of the DFT results. We show that the symmetry enforced band crossings at
$\Gamma$ and $A$ are double Weyl points, implying Chern bands for $k_z\neq
0,\pi$. We map out the distribution of Berry curvature and quantum metric and
discuss their relation to the orbital character. For a specific set of
parameters we find a singular flat band.
A topological 'Thouless' pump represents the quantised motion of particles in
response to a slow, cyclic modulation of external control parameters. The
Thouless pump, like the quantum Hall effect, is of fundamental interest in
physics because it links physically measurable quantities, such as particle
currents, to geometric properties of the experimental system, which can be
robust against perturbations and thus technologically useful. So far,
experiments probing the interplay between topology and inter-particle
interactions have remained relatively scarce. Here we observe a Thouless-type
charge pump in which the particle current and its directionality inherently
rely on the presence of strong interactions. Experimentally, we utilise
fermionic atoms in a dynamical superlattice which traces a pump trajectory that
remains trivial in the non-interacting limit. Remarkably, the transferred
charge in the interacting system is half of its usual value in the
non-interacting case, in agreement with matrix-product-state simulations. Our
experiments suggest that Thouless charge pumps are promising platforms to gain
insights into interaction-driven topological transitions and topological
quantum matter.
Kagome-lattice magnets $R$Mn$_6$Sn$_6$ recently emerged as a new platform to
exploit the interplay between magnetism and topological electronic states. Some
of the most exciting features of this family are the dramatic dependence of the
easy magnetization direction on the rare-earth specie and the kagome geometry
of the Mn planes that in principle can generate flat bands and Dirac points;
gapping of the Dirac points by spin-orbit coupling has been suggested recently
to be responsible for the observed anomalous Hall response in the member
TbMn$_6$Sn$_6$. In this paper, we address both issues with ab initio
calculations. We have discovered the significant role played by higher-order
crystal-field parameters and rare-earth magnetic anisotropy constants in these
systems. We demonstrate that the microscopic origin of rare-earth anisotropy
can also be quantified and understood at various levels: ab initio,
phenomenological, and analytical. In particular, using a simple and physically
transparent analytical model, we explain, with full quantitative agreement, the
evolution of anisotropy across the series. We analyze the topological
properties of Mn-dominated bands and demonstrate how they emerge from the
multiorbital planar kagome model. We further show that the most pronounced
quasi-2D dispersion are too far removed from the Fermi level, and therefore
cannot explain the observed quasi-2D anomalous Hall effect. By employing ab
initio many-body approaches, we demonstrate that the exchange-correlation
effects for itinerant Mn-$d$ electrons do not significantly alter the obtained
electronic and magnetic structure. Therefore, we conclude that, contrary to
previous claims, the most pronounced 2D kagome-derived topological band
features bear little relevance to transport in $R$Mn$_6$Sn$_6$, albeit they may
possibly be brought to focus by electron or hole doping.
Kagome metals AV3Sb5 (where the A can stand for K, Cs, or Rb) display a rich
phase diagram of correlated electron states, including superconductivity and
density waves. Within this landscape, recent experiments revealed signs of a
transition below approximately 35 K attributed to an electronic nematic phase
that spontaneously breaks rotational symmetry of the lattice. Here, we show
that rotational symmetry breaking initiates universally at a high temperature
in these materials, toward the 2 x 2 charge density wave transition
temperature. We do this via spectroscopic-imaging scanning tunneling microscopy
and study atomic-scale signatures of electronic symmetry breaking across
several materials in the AV3Sb5 family: CsV3Sb5, KV3Sb5 and Sn-doped CsV3Sb5.
Below a significantly lower temperature of about 30 K, we measure quantum
interference of quasiparticles, a key signature for the formation of a coherent
electronic state. These quasiparticles display a pronounced unidirectional
feature in reciprocal space that strengthens as the superconducting state is
approached. Our experiments reveal that high-temperature rotation symmetry
breaking and the charge ordering states are separated from the superconducting
ground state by an intermediate-temperature regime with coherent unidirectional
quasiparticles. This picture is phenomenologically different compared to that
in high-temperature superconductors, shedding light on the complex nature of
rotation symmetry breaking in AV3Sb5 kagome superconductors.
Hydrogen (H) plays a key role in the near-to-room temperature
superconductivity of hydrides at megabar pressures. This suggests that H doping
could have similar effects on the electronic and phononic spectra of materials
at ambient pressure as well. Here, we demonstrate the non-volatile control of
the electronic ground state of titanium diselenide (1T-TiSe$_2$) via ionic
liquid gating-driven H intercalation. This protonation induces a
superconducting phase, observed together with a charge-density wave through
most of the phase diagram, with nearly doping-independent transition
temperatures. The H-induced superconducting phase is possibly gapless-like and
multi-band in nature, in contrast with those induced in TiSe$_2$ via copper,
lithium, and electrostatic doping. This unique behavior is supported by ab
initio calculations showing that high concentrations of H dopants induce a full
reconstruction of the bandstructure, although with little coupling between
electrons and high-frequency H phonons. Our findings provide a promising
approach for engineering the ground state of transition metal dichalcogenides
and other layered materials via gate-controlled protonation.
Two-dimensional (2D) transition metal dichalcogenides (TMDC) and their
moir\'e interfaces have been demonstrated for correlated electron states,
including Mott insulators and electron/hole crystals commensurate with moir\'e
superlattices. Here we present spectroscopic evidences for ordered bosons -
interlayer exciton crystals in a WSe2/MoSe2/WSe2 trilayer, where the enhanced
Coulomb interactions over those in heterobilayers have been predicted to result
in exciton ordering. While the dipolar interlayer excitons in the heterobilayer
may be ordered by the periodic moir\'e traps, their mutual repulsion results in
de-trapping at exciton density n_ex larger than 10^11 cm^-2 to form mobile
exciton gases and further to electron-hole plasmas, both accompanied by
broadening in photoluminescence (PL) peaks and large increases in mobility. In
contrast, ordered interlayer excitons in the trilayer are characterized by
negligible mobility and by sharper PL peaks persisting to n_ex approximately
10^12 cm^-2. We present evidences for the predicted quadrupolar exciton crystal
and its transitions to dipolar excitons either with increasing n_ex or by an
applied electric field. These ordered interlayer excitons may serve as models
for the exploration of quantum phase transitions and quantum coherent
phenomena.
We study flows of barotropic perfect fluid under the simultaneous action of
the electromagnetic field and the axial-vector potential, the external field
conjugate to the fluid helicity. We obtain the deformation of the Euler
equation by the axial-vector potential and the deformations of various currents
by two external fields. We show that the divergence of the vector and axial
currents are controlled by the chiral anomaly known in quantum field theories
with Dirac fermions. We obtain these results by extending the variational
principle for barotropic flows of a perfect fluid by coupling with the external
axial-vector potential.
The observation, design and analysis of mesh-like networks in bionics,
polymer physics and biological systems has brought forward an extensive catalog
of fascinating structures of which a subgroup share a particular, yet
critically under appreciated attribute: being embedded in space such that one
wouldn't be able to pull them apart without prior removal of a subset of edges,
a state which we here call ensnarled. In this study we elaborate on a graph
theoretical method to analyze ensnarled finite, 2-component nets on the basis
of Hopf-link identification. Doing so we are able to construct an edge priority
operator, derived from the linking numbers of the spatial graphs' cycle bases,
which highlights critical edges. On its basis we developed a greedy algorithm
which identifies optimal edge removals to achieve unlinking, allowing for the
establishment of a new topological metric characterizing the state of ensnarled
network pairs.
Semiconductor artificial graphene nanostructures where Hubbard model
parameter $U/t$ can be of the order of 100, provide a highly controllable
platform to study strongly correlated quantum many-particle phases. We use
accurate variational and diffusion Monte Carlo methods to demonstrate a
transition from antiferromagnetic to metallic phases for experimentally
accessible lattice constant $a=50$ nm in terms of lattice site radius $\rho$,
for finite sized artificial honeycomb structures containing up to 114
electrons. By analysing spin-spin correlation functions, we show that edge
type, geometry and charge nonuniformity affect the steepness and the crossover
$\rho$ value of the phase transition. For triangular structures, the
metal-insulator transition is accompanied with a smoother edge polarization
transition.
We study Josephson junctions based on InSb nanowires with Sn shells. We
observe skewed critical current diffraction patterns: the maxima in forward and
reverse current bias are at different magnetic flux, with a displacement of
20-40 mT. The skew is greatest when the external field is nearly perpendicular
to the nanowire, in the substrate plane. This orientation suggests that
spin-orbit interaction plays a role. We develop a phenomenological model and
perform tight-binding calculations, both methods reproducing the essential
features of the experiment. The effect modeled is the $\phi$0-Josephson
junction with higher-order Josephson harmonics. The system is of interest for
Majorana studies: the effects are either precursor to or concomitant with
topological superconductivity. Current-phase relations that lack inversion
symmetry can also be used to design quantum circuits with engineered
nonlinearity.
Two-dimensional (2D) model of a weak topological insulator with $N$-stacked
Su-Schrieffer-Heeger (SSH) chain is studied. This study starts with a basic
model with all the fundamental symmetries (chiral, time-reversal, and
particle-hole) preserved. Different topological phases are introduced in this
model by systematically breaking the system's symmetries. The symmetries are
broken by introducing different bonds (hopping terms) in the system. First, the
chiral symmetry is broken by introducing hopping within each sub-lattice or
intra-sub-lattice hopping, where the hopping strengths of the sub-lattices are
equal in magnitudes but opposite in sign. Then, following Haldane, the
time-reversal (TR) symmetry is broken by replacing the real intra-sub-lattice
hopping strengths with imaginary numbers without changing the magnitudes. We
find that breaking chiral and TR symmetries are essential for the weak
topological insulator to be a Chern insulator. These models exhibit nontrivial
topology with the Chern number $C = \pm 1$. The preservation of the
particle-hole (PH) symmetry in the system facilitates an analytical calculation
of $C$, which agrees with the numerically observed topological phase transition
in the system. An interesting class of topologically nontrivial systems with
$C=0$ is also observed, where the non-triviality is identified by quantized and
fractional 2D Zak phase. Finally, the PH symmetry is broken in the system by
introducing unequal amplitudes of intra-sub-lattice hopping strengths, while
the equal intra-sub-lattice hopping strengths ensures the preservation of the
inversion symmetry. We investigate the interplay of the PH and the inversion
symmetries in the topological phase transition. A discussion on the possible
experimental realizations of this model is also presented.
With the Becchi-Rouet-Stora-Tyutin (BRST) quantization of gauge theory, we
solve the long-standing difficult problem of the local constraint conditions,
i.e., the single occupation of a slave particle per site, in the slave particle
theory. This difficulty is actually caused by inconsistently dealing with the
local Lagrange multiplier $\lambda_i$ which ensures the constraint: In the
Hamiltonian formalism of the theory, $\lambda_i$ is time-independent and
commutes with the Hamiltonian while in the Lagrangian formalism, $\lambda_i(t)$
becomes time-dependent and plays a role of gauge field. This implies that the
redundant degrees of freedom of $\lambda_i(t)$ are introduced and must be
removed by the additional constraint, the gauge fixing condition $\partial_t
\lambda_i(t)=0$. In literature, this gauge fixing condition was missed. We add
this gauge fixing condition and use the BRST quantization of gauge theory for
Dirac's first-class constraints in the slave particle theory. This gauge fixing
condition endows $\lambda_i(t)$ with dynamics and leads to important physical
results. As an example, we study the Hubbard model at half-filling and find
that the spinon is gapped in the weak $U$ and the system is indeed a
conventional metal, which resolves the paradox that the weak coupling state is
a superconductor in the previous slave boson mean field theory. For the $t$-$J$
model, we find that the dynamic effect of $\lambda_i(t)$ substantially
suppresses the $d$-wave pairing gap and then the superconducting critical
temperature may be lowered at least a factor of one-fifth of the mean field
value which is of the order of 1000 K. The renormalized $T_c$ is then close to
that in cuprates.
Due to its incommensurate nature, moir\'e superlattices host not only
acoustic phonons but also another type of soft collective modes called phasons.
Here, we investigate the impact of electron-phason scattering on the transport
properties of moir\'e systems. We show that the resistivity can scale linearly
with temperature down to temperatures much lower than the Bloch-Gr\"uneisen
scale defined by electron kinematics on the Fermi surface. This result stems
from the friction between layers, which transfers phason spectral weight to a
broad diffusive low-energy peak in the mechanical response of the system. As a
result, phason scattering becomes a very efficient channel for entropy
production at low temperatures. We also consider the contributions of phasons
to thermodynamic properties at low temperatures and find a ''metallic-like''
linear-in-$T$ behavior for the specific heat, despite the fact that this
behavior is due to mechanical and not electronic degrees of freedom. We discuss
the implications of this finding to reports of linear-in-$T$ resistivity in the
phase diagram of twisted bilayer graphene.
Long and stable timescales are often observed in complex biochemical
networks, such as in emergent oscillations. How these robust dynamics persist
remains unclear, given the many stochastic reactions and shorter time scales
demonstrated by underlying components. We propose a topological model with
parsimonious parameters that produces long oscillations around the network
boundary, effectively reducing the system dynamics to a lower-dimensional
current. Using this to model KaiC, which regulates the circadian rhythm in
cyanobacteria, we compare the coherence of oscillations to that in other KaiC
models. Our topological model localizes currents on the system edge for an
efficient regime with simultaneously increased precision and decreased cost.
Further, we introduce a new predictor of coherence from the analysis of
spectral gaps, and show that our model saturates a global thermodynamic bound.
Our work presents a new mechanism for emergent oscillations in complex
biological networks utilizing dissipative cycles to achieve robustness and
efficient performance.
Josephson tunnel junctions exhibit a supercurrent typically proportional to
the sine of the superconducting phase difference $\phi$. In general, a term
proportional to $\cos(\phi)$ is also present, alongside microscopic electronic
retardation effects. We show that voltage pulses sharply varying in time prompt
a significant impact of the $\cos(\phi)$ term. Its interplay with the
$\sin(\phi)$ term results in a non-equilibrium fractional Josephson effect
(NFJE) $\sim\sin(\phi/2)$ in the presence of bound states close to zero
frequency. Our microscopic analysis reveals that the interference of
non-equilibrium virtual quasiparticle excitations is responsible for this
phenomenon. We also analyse this phenomenon for topological Josephson junctions
with Majorana bound states. Remarkably, the NFJE is independent of the ground
state fermion parity unlike its equilibrium counterpart.
We theoretically explore the Floquet generation of Majorana end modes~(MEMs)
(both regular $0$- and anomalous $\pi$-modes) implementing a periodic
sinusoidal modulation in chemical potential in an experimentally feasible setup
based on a one-dimensional chain of magnetic impurity atoms having spin spiral
configuration (out-of-plane N\'eel-type) fabricated on the surface of most
common bulk $s$-wave superconductor. We obtain a rich phase diagram in the
parameter space, highlighting the possibility of generating multiple
$0$-/$\pi$-MEMs localized at the end of the chain. We also study the real-time
evolution of these emergent MEMs, especially when they start to appear in the
time domain. These MEMs are topologically characterized by employing the
dynamical winding number. We observe that the existing perturbative analysis is
unable to explain the numerical findings, indicating the complex mechanism
behind the formation of the Floquet Shiba minigap, which is characteristically
distinct from other setup e.g. Rashba nanowire model. We also discuss the
possible experimental parameters in connection to our model. Our work paves the
way to realize the Floquet MEMs in a magnet-superconductor heterostructure.
The Benalcazar-Bernevig-Hughes (BBH) model [Science 357, 61 (2017)],
featuring bulk quadrupole moment, edge dipole moments, and corner states, is a
paradigm of both higher-order topological insulators and topological multipole
insulators. In this work, we generalize the BBH model to arbitrary dimensions
and demonstrate the bulk multipole moment. In our demonstration, the analytical
solution of corner states can be directly constructed, which possesses a
unified and elegant form. Based on the corner states solution and chiral
symmetries analysis, we develop a general boundary projection method to extract
the boundary Hamiltonians, which thoroughly reveals the boundary-localized
multipole moments of lower dimension, the hallmark of topological multipole
insulators. Our work facilitates the unified understanding of topological
multipole insulators and unveils their cascade hierarchy versatilely.
Recent experiments on Bernal bilayer graphene (BLG) deposited on monolayer
WSe$_2$ revealed robust, ultra-clean superconductivity coexisting with sizable
induced spin-orbit coupling. Here we propose BLG/WSe$_2$ as a platform to
engineer gate-defined planar topological Josephson junctions, where the normal
and superconducting regions descend from a common material. More precisely, we
show that if superconductivity in BLG/WSe$_2$ is gapped and emerges from a
parent state with inter-valley coherence, then Majorana zero modes can form in
the barrier region upon applying weak in-plane magnetic fields. Our results
spotlight a potential pathway for `internally engineered' topological
superconductivity that minimizes detrimental disorder and
orbital-magnetic-field effects.
Hybridizing superconductivity with the quantum Hall (QH) effects has major
potential for designing novel circuits capable of inducing and manipulating
non-Abelian states for topological quantum computation. However, despite recent
experimental progress towards this hybridization, concrete evidence for a
chiral QH Josephson junction -- the elemental building block for coherent
superconducting-QH circuits -- is still lacking. Its expected signature is an
unusual chiral supercurrent flowing in QH edge channels, which oscillates with
a specific $2\phi_0$ magnetic flux periodicity ($\phi_0=h/2e$ is the
superconducting flux quantum, $h$ the Planck constant and $e$ the electron
charge). Here, we show that ultra-narrow Josephson junctions defined in
encapsulated graphene nanoribbons exhibit such a chiral supercurrent, visible
up to 8 teslas, and carried by the spin-degenerate edge channel of the QH
plateau of resistance $h/2e^2\simeq 12.9$ k$\Omega$. We observe reproducible
$2\phi_0$-periodic oscillation of the supercurrent, which emerges at constant
filling factor when the area of the loop formed by the QH edge channel is
constant, within a magnetic-length correction that we resolve in the data.
Furthermore, by varying the junction geometry, we show that reducing the
superconductor/normal interface length is pivotal to obtain a measurable
supercurrent on QH plateaus, in agreement with theories predicting dephasing
along the superconducting interface. Our findings mark a critical milestone
along the path to explore correlated and fractional QH-based superconducting
devices that should host non-Abelian Majorana and parafermion zero modes.
We present the design, fabrication and discuss the performance of a new
combined high-resolution Scanning Tunneling and thermopower Microscope
(STM/SThEM). We also describe the development of the electronic control, the
user interface, the vacuum system, and arrangements to reduce acoustical noise
and vibrations. We demonstrate the microscope performance with
atomic-resolution topographic images of Highly oriented pyrolytic graphite
(HOPG) and local thermopower measurements in the semimetal Bi2Te3 sample. Our
system offers a tool to investigate the relationship between electronic
structure and thermoelectric properties at the nanoscale.
The stability and dynamics of almost strong zero and $\pi$ modes in weakly
non-integrable Floquet spin chains are investigated. Such modes can also be
viewed as localized Majorana modes at the edge of a topological superconductor.
Perturbation theory in the strength of integrability-breaking interaction $J_z$
is employed to estimate the decay rates of these modes, and compared to decay
rates obtained from exact diagonalization. The structure of the perturbation
theory and thus the lifetime of the modes is governed by the conservation of
quasi-energy modulo $2 \pi/T$, where $T$ is the period of the Floquet system.
If the quasi-energies of minimally $4 n-1$ quasi-particles adds up to zero (or
$\pi/T$ for a $\pi$ mode), the lifetime is proportional to $1/J_z^{2 n}$. Thus
the lifetime is sensitively controlled by the width of the single-particle
Floquet bands. For regimes where the decay rates are quadratic in $J_z$, an
analytic expression for the decay rate in terms of an infinite temperature
autocorrelation function of the integrable model is derived, and shown to agree
well with exact diagonalization.
Since dissipative processes are ubiquitous in semiconductors, characterizing
how electronic and thermal energy transduce and transport at the nanoscale is
vital for understanding and leveraging their fundamental properties. For
example, in low-dimensional transition metal dichalcogenides (TMDCs), excess
heat generation upon photoexcitation is difficult to avoid since even with
modest injected exciton densities, exciton-exciton annihilation still occurs.
Both heat and photoexcited electronic species imprint transient changes in the
optical response of a semiconductor, yet the unique signatures of each are
difficult to disentangle in typical spectra due to overlapping resonances. In
response, we employ stroboscopic optical scattering microscopy (stroboSCAT) to
simultaneously map both heat and exciton populations in few-layer \ch{MoS2} on
relevant nanometer and picosecond length- and time scales and with 100-mK
temperature sensitivity. We discern excitonic contributions to the signal from
heat by combining observations close to and far from exciton resonances,
characterizing photoinduced dynamics for each. Our approach is general and can
be applied to any electronic material, including thermoelectrics, where heat
and electronic observables spatially interplay, and lays the groundwork for
direct and quantitative discernment of different types of coexisting energy
without recourse to complex models or underlying assumptions.
Gauging a finite Abelian normal subgroup $\Gamma$ of a nonanomalous 0-form
symmetry $G$ of a theory in $(d+1)$D spacetime can yield an unconventional
critical point if the original theory has a continuous transition where
$\Gamma$ is completely spontaneously broken and if $G$ is a nontrivial
extension of $G/\Gamma$ by $\Gamma$. The gauged theory has symmetry $G/\Gamma
\times \hat{\Gamma}^{(d-1)}$, where $\hat{\Gamma}^{(d-1)}$ is the $(d-1)$-form
dual symmetry of $\Gamma$, and a 't Hooft anomaly between them. Thus it can be
viewed as a boundary of a topological phase protected by $G/\Gamma \times
\hat{\Gamma}^{(d-1)}$. The ordinary critical point, upon gauging, is mapped to
a deconfined quantum critical point between two ordinary symmetry-breaking
phases ($d =1$) or an unconventional quantum critical point between an ordinary
symmetry-breaking phase and a topologically ordered phase ($d\ge 2$) associated
with $G/\Gamma$ and $\hat{\Gamma}^{(d-1)}$, respectively. Order parameters and
disorder parameters, before and after gauging, can be directly related. As a
concrete example, we gauge the $\mathbb{Z}_2$ subgroup of $\mathbb{Z}_4$
symmetry of a 4-state clock model on a 1D lattice and a 2D square lattice.
Since the symmetry of the clock model contains $D_8$, the dihedral group of
order 8, we also analyze the anomaly structure which is similar to that in the
compactified $SU(2)$ gauge theory with $\theta =\pi$ in $(3+1)$D and its mixed
gauge theory. The general case is also discussed.
The ferromagnetic Weyl semimetals, such as Co3Sn2S2, feature pairs of Weyl
points characterized by the opposite chiralities.We model this type of
semimetals by the inversion symmetry protected and the time reversal symmetry
broken Bloch Hamiltonian. It involves terms representing the tunnelling effect,
exchange field corresponding to the ferromagnetic order, chirality index of
Weyl points with related energy parameter, and the angle formed by the spin
magnetic moments and the axis perpendicular to the system-plane. While the
in-plane spin order lacks the presence of the Weyl nodes at some points in the
Brillouin zone, the bands of opposite chirality almost linearly cross each
other with band inversion at Weyl points above and below the Fermi level for
the order along the perpendicular axis. We also show that in the absence of the
exchange field, the incidence of the circularly polarized radiation leads to
the emergence of a novel state with broken time reversal symmetry.
We consider a massive fermionic quantum field localized on a plane in
external constant and homogeneous electric and magnetic fields. The magnetic
field is perpendicular to the plane and the electric field is parallel. The
complete set of solutions to the Dirac equation is presented. As important
physical characteristics of the vacuum state, the fermion condensate and the
expectation value of the energy-momentum tensor are investigated. The
renormalization is performed using the Hurwitz function. The results are
compared with those previously studied in the case of zero electric field. We
discuss the behavior of the vacuum expectation values in different regions for
the values of the problem parameters. Applications of the results include the
electronic subsystem of graphene sheet described by the Dirac model in the
long-wavelength approximation.
The random-field spin-1/2 XXZ chains, and the corresponding Anderson
insulators of spinless fermions with density-density interaction, have been
intensively studied in the context of many-body localization. However, we
recently argued [B. Krajewski et al., Phys. Rev. Lett. 129, 260601(2022)] that
the two-body density-density interaction in these models is not generic since
only a small fraction of this interaction represents a true local perturbation
to the Anderson insulator. Here we study ergodicity of strongly disordered
Anderson insulator chains choosing other forms of the two-body interaction for
which the strength of the true perturbation is of the same order of magnitude
as the bare two-body interaction. Focusing on the strong interaction regime,
numerical results for the level statistics and the eigenstate thermalization
hypothesis are consistent with emergence of ergodicity at arbitrary strong
disorder.
Originating from the topology of the path-integral target space $Y$,
solitonic symmetry describes the conservation law of topological solitons and
the selection rule of defect operators. As Ref.~\cite{Chen:2022cyw}
exemplifies, the conventional treatment of solitonic symmetry as an invertible
symmetry based on homotopy groups is inappropriate. In this paper, we develop a
systematic framework to treat solitonic symmetries as non-invertible
generalized symmetries. We propose that the non-invertible solitonic symmetries
are generated by the partition functions of auxiliary topological quantum field
theories (TQFTs) coupled with the target space $Y$. We then understand
solitonic symmetries as non-invertible cohomology theories on $Y$ with TQFT
coefficients. This perspective enables us to identify the invertible solitonic
subsymmetries and also clarifies the topological origin of the
non-invertibility in solitonic symmetry. We finally discuss how solitonic
symmetry relies on and goes beyond the conventional wisdom of homotopy groups.
This paper is aimed at a tentative general framework for solitonic symmetry,
serving as a starting point for future developments.
The coexistence of multiple structural phases and field induced short-range
to long-range order transition in ferroelectric materials, leads to a strong
electrocaloric effect (ECE) and electrical energy storage density (Wrec) in the
vicinity of ferroelectric to non-ergodic phase transition in NKBT ceramic.
Structural analysis using X-ray diffraction, Raman spectroscopy and TEM studies
ascertained the coexistence of tetragonal (P4mm) and rhombohedral (R3c) phases.
Dielectric study has revealed a critical slowing down of polar domain dynamics
below a diffuse phase transition. Present investigation reports ECE in
lead-free (Na0.8K0.2)0.5Bi0.5TiO3 (NKBT) ceramic by direct and indirect
methods, which confirm the multifunctional nature of NKBT and its usefulness
for applications in refrigeration and energy storage. A direct method of EC
measurement in NKBT ceramic exhibits significant adiabatic temperature change
({\Delta}T) ~ 1.10 K and electrocaloric strength ({\xi}) ~ 0.55 Kmm/kV near the
ferroelectric to non-ergodic phase transition at an external applied field of
20 kV/cm. A highest recoverable energy (Wrec) ~ 0.78 J/cm3 and electrical
storage efficiency ({\eta}) ~ 86% are achieved at 423 K and an applied field of
20 kV/cm. This behavior is ascribed to the delicate balance between the field
induced order-disordered transition and the thermal energy needed to disrupt
field induced co-operative interaction.

Date of feed: Tue, 08 Aug 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]+) **An Effective Hydrodynamic Description of Marching Locusts. (arXiv:2308.02589v1 [q-bio.QM])**

Dan Gorbonos, Felix Oberhauser, Luke L. Costello, Yannick Günzel, Einat Couzin-Fuchs, Benjamin Koger, Iain D. Couzin

**Nature of even and odd magic angles in helical twisted trilayer graphene. (arXiv:2308.02638v1 [cond-mat.mes-hall])**

Daniele Guerci, Yuncheng Mao, Christophe Mora

**Observation of Fractionally Quantized Anomalous Hall Effect. (arXiv:2308.02657v1 [cond-mat.mes-hall])**

Heonjoon Park, Jiaqi Cai, Eric Anderson, Yinong Zhang, Jiayi Zhu, Xiaoyu Liu, Chong Wang, William Holtzmann, Chaowei Hu, Zhaoyu Liu, Takashi Taniguchi, Kenji Watanabe, Jiun-haw Chu, Ting Cao, Liang Fu, Wang Yao, Cui-Zu Chang, David Cobden, Di Xiao, Xiaodong Xu

**Nonlinear wave propagation in large extra spatial dimensions and the blackbody thermal laws. (arXiv:2308.02685v1 [hep-th])**

I. Soares, R. Turcati, S. B. Duarte

**Screened plasmons of graphene near a perfect electric conductor. (arXiv:2308.02691v1 [physics.optics])**

Afshin Moradi, Nurhan Turker Tokan

**The role of Coulomb interaction on the electronic properties of monolayer NiX$_2$ (X = S, Se): A DFT+U+V study. (arXiv:2308.02737v1 [cond-mat.mes-hall])**

Sergio Bravo, P.A. Orellana, L. Rosales

**Probing charge order of monolayer NbSe$_2$ within a bulk crystal. (arXiv:2308.02772v1 [cond-mat.mtrl-sci])**

Doron Azoury, Edoardo Baldini, Aravind Devarakonda, Jiarui Li, Shiang Fang, Pheona Williams, Riccardo Comin, Joseph Checkelsky, Nuh Gedik

**Quasiparticle and Transport Properties of Disordered Bilayer Graphene. (arXiv:2308.02779v1 [cond-mat.dis-nn])**

Yanru Chen, Bo Fu, Jinrong Xu, Qinwei Shi, Ping Cui, Zhenyu Zhang

**Shape-dependent friction scaling laws in twisted layered material interfaces. (arXiv:2308.02818v1 [physics.app-ph])**

Weidong Yan, Xiang Gao, Wengen Ouyang, Ze Liu, Oded Hod, Michael Urbakh

**Fractional quantum Hall effect in valley-layer locked Landau levels in bilayer MoS$_{2}$. (arXiv:2308.02821v1 [cond-mat.mes-hall])**

Siwen Zhao, Jinqiang Huang, Valentin Crépel, Xingguang Wu, Tongyao Zhang, Hanwen Wang, Xiangyan Han, Zhengyu Li, Chuanying Xi, Senyang Pan, Zhaosheng Wang, Kenji Watanabe, Takashi Taniguchi, Benjamin Sacépé, Jing Zhang, Ning Wang, Jianming Lu, Nicolas Regnault, Zheng Vitto Han

**Nonequilibrium thermodynamic signatures of collective dynamical states around chimera in a chemical reaction network. (arXiv:2308.02857v1 [cond-mat.stat-mech])**

Premashis Kumar, Gautam Gangopadhyay

**A powered full quantum eigensolver for energy band structures. (arXiv:2308.03134v1 [cond-mat.mtrl-sci])**

Bozhi Wang, Jingwei Wen, Jiawei Wu, Haonan Xie, Fan Yang, Shijie Wei, Gui-lu Long

**Magic Angles and Fractional Chern Insulators in Twisted Homobilayer TMDs. (arXiv:2308.03143v1 [cond-mat.str-el])**

Nicolás Morales-Durán, Nemin Wei, Allan H. MacDonald

**Core-shell nanocrystals for plasmon-enhanced photodetection in the graphene-based hybrid photodetector. (arXiv:2308.03167v1 [cond-mat.mtrl-sci])**

Anima Ghosh, Shyam Narayan Singh Yadav, Ming-Hsiu Tsai, Abhishek Dubey, Shangjr Gwo, Chih-Ting Lin, Ta- Jen Yen

**Breakdown of Chiral Edge Modes in Topological Magnon Insulators. (arXiv:2308.03168v1 [cond-mat.str-el])**

Jonas Habel (1 and 2), Alexander Mook (3 and 1), Josef Willsher (1 and 2), Johannes Knolle (1 and 2 and 4) ((1) Technical University of Munich, (2) Munich Center for Quantum Science and Technology, (3) Johannes Gutenberg-University Mainz, (4) Blackett Laboratory London)

**Terahertz chiral metamaterial cavities breaking time-reversal symmetry. (arXiv:2308.03195v1 [cond-mat.mes-hall])**

Johan Andberger, Lorenzo Graziotto, Luca Sacchi, Mattias Beck, Giacomo Scalari, Jérôme Faist

**Quadrupolar Excitons and Hybridized Interlayer Mott Insulator in a Trilayer Moir\'e Superlattice. (arXiv:2308.03219v1 [cond-mat.mes-hall])**

Zhen Lian, Dongxue Chen, Lei Ma, Yuze Meng, Ying Su, Li Yan, Xiong Huang, Qiran Wu, Xinyue Chen, Mark Blei, Takashi Taniguchi, Kenji Watanabe, Sefaattin Tongay, Chuanwei Zhang, Yong-Tao Cui, Su-Fei Shi

**Hydrogen Transport Between Layers of Transition Metal-Dichalcogenides. (arXiv:2308.03418v1 [cond-mat.mtrl-sci])**

Ismail Eren, Yun An, Agnieszka B. Kuc

**How to enhance anomalous Hall effects in magnetic Weyl semimetal Co$_3$Sn$_2$S$_2$?. (arXiv:2308.03483v1 [cond-mat.mtrl-sci])**

Shivam Rathod, Megha Malasi, Archana Lakhani, Devendra Kumar

**Abelian and non-Abelian quantum spin liquids in a three-component Bose gas on optical Kagome lattices. (arXiv:2308.03509v1 [cond-mat.quant-gas])**

Kaiye Shi, Wei Zhang, Zheng-Xin Liu

**Fusion Mechanism for Quasiparticles and Topological Quantum Order in the Lowest-Landau-Level. (arXiv:2308.03548v1 [cond-mat.str-el])**

Arkadiusz Bochniak, Gerardo Ortiz

**Phase separation in tilings of a bounded region of the plane. (arXiv:2308.03552v1 [cond-mat.stat-mech])**

Eduardo J. Aguilar, Valmir C. Barbosa, Raul Donangelo, Sergio R. Souza

**Tuning the initial phase to control the final state of a driven qubit: single-passage coherent destruction of tunneling. (arXiv:2308.03571v1 [quant-ph])**

Polina Kofman, Sergey Shevchenko, Franco Nori

**Detection of nontrivial topology driven by charge density wave in a semi-Dirac metal. (arXiv:2308.03587v1 [cond-mat.mtrl-sci])**

Rafiqul Alam#, Prasun Boyal1, Shubhankar Roy, Ratnadwip Singha, Buddhadeb Pal, Riju Pal, Prabhat Mandal, Priya Mahadevan, Atindra Nath Pal

**Single crystal growth and characterization of antiferromagnetically ordering EuIn$_2$. (arXiv:2308.03600v1 [cond-mat.mtrl-sci])**

Brinda Kuthanazhi, Simon X. M. Riberolles, Dominic H. Ryan, Philip J. Ryan, Jong-Woo Kim, Lin-Lin Wang, Robert J. McQueeney, Benjamin G. Ueland, Paul C. Canfield

**Half-quantum flux in spin-triplet superconducting rings with bias current. (arXiv:2308.03668v1 [cond-mat.supr-con])**

Kazushi Aoyama

**Analytic density of states of two-dimensional Chern insulator. (arXiv:2308.03681v1 [cond-mat.str-el])**

Vera Uzunova, Krzysztof Byczuk

**Half-valley Ohmic Contact and Contact-Limited Valley-Contrasting Current Injection. (arXiv:2308.03700v1 [cond-mat.mes-hall])**

Xukun Feng, Shi-Jun Liang, Chit Siong Lau, Ching Hua Lee, Shengyuan A. Yang, Yee Sin Ang

**Inhomogeneous high temperature melting and decoupling of charge density waves in spin-triplet superconductor UTe2. (arXiv:2308.03721v1 [cond-mat.supr-con])**

Alexander LaFleur, Hong Li, Corey E. Frank, Muxian Xu, Siyu Cheng, Ziqiang Wang, Nicholas P. Butch, Ilija Zeljkovic

**Tight-binding models for SG 143 (P3) and application to recent DFT results on copper-doped lead apatite. (arXiv:2308.03751v1 [cond-mat.mes-hall])**

Moritz M. Hirschmann, Johannes Mitscherling

**Interaction-induced charge pumping in a topological many-body system. (arXiv:2308.03756v1 [cond-mat.quant-gas])**

Konrad Viebahn, Anne-Sophie Walter, Eric Bertok, Zijie Zhu, Marius Gächter, Armando A. Aligia, Fabian Heidrich-Meisner, Tilman Esslinger

**Interplay between magnetism and band topology in Kagome magnets $R$Mn$_6$Sn$_6$. (arXiv:2201.11265v3 [cond-mat.mtrl-sci] UPDATED)**

Y. Lee, R. Skomski, X. Wang, P. P. Orth, Y. Ren, Byungkyun Kang, A. K. Pathak, A. Kutepov, B. N. Harmon, R. J. McQueeney, I. I. Mazin, Liqin Ke

**Unidirectional coherent quasiparticles in the high-temperature rotational symmetry broken phase of AV3Sb5 kagome superconductors. (arXiv:2203.15057v2 [cond-mat.str-el] UPDATED)**

Hong Li, He Zhao, Brenden Ortiz, Yuzki Oey, Ziqiang Wang, Stephen D. Wilson, Ilija Zeljkovic

**Superconductivity induced by gate-driven hydrogen intercalation in the charge-density-wave compound 1T-TiSe2. (arXiv:2205.12951v4 [cond-mat.supr-con] UPDATED)**

Erik Piatti, Giacomo Prando, Martina Meinero, Cesare Tresca, Marina Putti, Stefano Roddaro, Gianrico Lamura, Toni Shiroka, Pietro Carretta, Gianni Profeta, Dario Daghero, Renato S. Gonnelli

**Evidence for Exciton Crystals in a 2D Semiconductor Heterotrilayer. (arXiv:2207.09601v3 [cond-mat.mes-hall] UPDATED)**

Yusong Bai, Yiliu Li, Song Liu, Yinjie Guo, Jordan Pack, Jue Wang, Cory R. Dean, James Hone, X.-Y. Zhu

**Anomalies in fluid dynamics: flows in a chiral background via variational principle. (arXiv:2207.10195v2 [hep-th] UPDATED)**

Alexander G. Abanov, Paul B. Wiegmann

**Ensnarled: On the topological linkage of spatially embedded network pairs. (arXiv:2208.11662v2 [q-bio.TO] UPDATED)**

Felix Kramer, Carl D Modes

**Quantum Monte Carlo Study of Semiconductor Artificial Graphene Nanostructures. (arXiv:2210.14696v2 [cond-mat.mes-hall] UPDATED)**

Gökhan Öztarhan, E. Bulut Kul, Emre Okcu, A. D. Güçlü

**Evidence of $\phi$0-Josephson junction from skewed diffraction patterns in Sn-InSb nanowires. (arXiv:2212.00199v2 [cond-mat.mes-hall] UPDATED)**

B. Zhang, Z. Li, V. Aguilar, P. Zhang, M. Pendharkar, C. Dempsey, J. S. Lee, S. D. Harrington, S. Tan, J. S. Meyer, M. Houzet, C. J. Palmstrom, S. M. Frolov

**Cataloging topological phases of $N$-stacked Su-Schrieffer-Heeger chains by a systematic breaking of symmetries. (arXiv:2212.02095v2 [cond-mat.str-el] UPDATED)**

Aayushi Agrawal, Jayendra N. Bandyopadhyay

**Solving local constraint conditions in slave particle theory. (arXiv:2212.13734v3 [cond-mat.str-el] UPDATED)**

Xi Luo, Jianqiao Liu, Yue Yu

**Extended linear-in-$T$ resistivity due to electron-phason scattering in moir\'e superlattices. (arXiv:2302.00043v2 [cond-mat.mes-hall] UPDATED)**

Héctor Ochoa, Rafael M. Fernandes

**A topological mechanism for robust and efficient global oscillations in biological networks. (arXiv:2302.11503v2 [physics.bio-ph] UPDATED)**

Chongbin Zheng, Evelyn Tang

**Non-equilibrium fractional Josephson effect. (arXiv:2303.14385v2 [cond-mat.supr-con] UPDATED)**

Aritra Lahiri, Sang-Jun Choi, Björn Trauzettel

**Engineering anomalous Floquet Majorana modes and their time evolution in helical Shiba chain. (arXiv:2304.02352v2 [cond-mat.mes-hall] UPDATED)**

Debashish Mondal, Arnob Kumar Ghosh, Tanay Nag, Arijit Saha

**Generalization of Benalcazar-Bernevig-Hughes model to arbitrary dimensions. (arXiv:2304.07714v2 [cond-mat.mes-hall] UPDATED)**

Xun-Jiang Luo, Fengcheng Wu

**Gate-defined topological Josephson junctions in Bernal bilayer graphene. (arXiv:2304.11807v2 [cond-mat.mes-hall] UPDATED)**

Ying-Ming Xie, Étienne Lantagne-Hurtubise, Andrea F. Young, Stevan Nadj-Perge, Jason Alicea

**Evidence for chiral supercurrent in quantum Hall Josephson junctions. (arXiv:2305.01766v2 [cond-mat.mes-hall] UPDATED)**

Hadrien Vignaud, David Perconte, Wenmin Yang, Bilal Kousar, Edouard Wagner, Frédéric Gay, Kenji Watanabe, Takashi Taniguchi, Hervé Courtois, Zheng Han, Hermann Sellier, Benjamin Sacépé

**High-Resolution Scanning Tunneling Microscope and its Adaptation for Local Thermopower Measurements in 2D Materials. (arXiv:2305.03418v2 [cond-mat.mtrl-sci] UPDATED)**

Jose D. Bermúdez-Perez, Edwin Herrera-Vasco, Javier Casas-Salgado, Hector A. Castelblanco, Karen Vega-Bustos, Gabriel Cardenas-Chirivi, Oscar L. Herrera-Sandoval, Hermann Suderow, Paula Giraldo-Gallo, Jose A. Galvis

**Decay rates of almost strong modes in Floquet spin chains beyond Fermi's Golden Rule. (arXiv:2305.04980v2 [cond-mat.str-el] UPDATED)**

Hsiu-Chung Yeh, Achim Rosch, Aditi Mitra

**Detecting, distinguishing, and spatiotemporally tracking photogenerated charge and heat at the nanoscale. (arXiv:2305.13676v2 [cond-mat.mtrl-sci] UPDATED)**

Hannah L. Weaver, Cora M. Went, Joeson Wong, Dipti Jasrasaria, Eran Rabani, Harry A. Atwater, Naomi S. Ginsberg

**Boundary criticality via gauging finite subgroups: a case study on the clock model. (arXiv:2306.02976v3 [cond-mat.str-el] UPDATED)**

Lei Su

**Weyl Nodes of Opposite Chirality in Ferromagnetic WSM. (arXiv:2306.07882v2 [cond-mat.mes-hall] UPDATED)**

Udai Prakash Tyagi, Partha Goswami

**Fermionic condensate and the vacuum energy-momentum tensor for planar fermions in homogeneous electric and magnetic fields. (arXiv:2306.11402v2 [hep-th] UPDATED)**

V. V. Parazian

**Strongly disordered Anderson insulator chains with generic two-body interaction. (arXiv:2306.14613v2 [cond-mat.stat-mech] UPDATED)**

B. Krajewski, L. Vidmar, J. Bonca, M. Mierzejewski

**Solitonic symmetry as non-invertible symmetry: cohomology theories with TQFT coefficients. (arXiv:2307.00939v2 [hep-th] UPDATED)**

Shi Chen, Yuya Tanizaki

**Direct and Indirect methods of electrocaloric effect determination and energy storage calculation in (Na0.8K0.2)0.5Bi0.5TiO3 ceramic. (arXiv:2307.16232v2 [cond-mat.mtrl-sci] UPDATED)**

Pravin Varade, Adityanarayan H. Pandey, N. Shara Sowmya, S. M. Gupta, Abhay Bhisikar, N. Venkataramani, A. R. Kulkarni

Found 7 papers in prb Specific types of spatial defects or potentials can turn monolayer graphene into a topological material. These topological defects are classified by a spatial dimension $D$ and they are systematically obtained from the Hamiltonian by means of its symbol $\mathcal{H}(\mathbit{k},\mathbit{r})$, an ope… Allosterism traditionally refers to local changes in an extended object, for instance the binding of a ligand to a macromolecule, leading to a localized response at some other, possibly quite remote position. Here, we show that such fascinating effects may already occur in very simple and common qua… We study the intrinsic spin Hall effect of a Dirac Hamiltonian system with ferromagnetic exchange coupling, a minimal model combining relativistic spin-orbit interaction and ferromagnetism. The energy bands of the Dirac Hamiltonian are split after introducing a Stoner-type ferromagnetic ordering, wh… By first-principles calculations, we study the magnetic and topological properties of $\mathit{XY}{\mathrm{Bi}}_{2}{\mathrm{Te}}_{5}$-family $(X, Y=\mathrm{Mn},\mathrm{Ni},\mathrm{V},\mathrm{Eu})$ compounds. The strongly coupled double magnetic atom-layers can significantly enhance the magnetic orde… The effect of the energy valley on interlayer charge transfer in transition metal dichalcogenide (TMD) heterostructures is studied by transient absorption spectroscopy and density functional theory. First-principles calculations confirm that the ${\mathrm{Λ}}_{\text{min}}$ valley in the conduction b… Two-dimensional (2D) semiconductor materials offer a platform for unconventional applications such as valleytronics, flexible nanoelectronics, and hosts of quantum emitters. Many of these materials and their electronic properties remain to be explored. Using Effects of a bias electric current have been theoretically investigated in a spin-triplet superconducting ring in a magnetic field. Based on the Ginzburg-Landau theory, we show that the bias current can stabilize a half-quantum-flux (HQF) state via couplings to the Zeeman field and the dipole-type s…

Date of feed: Tue, 08 Aug 2023 03:17:08 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]+) **Defects in graphene: A topological description**

Amit Goft, Yuval Abulafia, Nadav Orion, Claude L. Schochet, and Eric Akkermans

Author(s): Amit Goft, Yuval Abulafia, Nadav Orion, Claude L. Schochet, and Eric Akkermans

[Phys. Rev. B 108, 054101] Published Mon Aug 07, 2023

**Allosteric impurity effects in long spin chains**

Christian Eidecker-Dunkel and Peter Reimann

Author(s): Christian Eidecker-Dunkel and Peter Reimann

[Phys. Rev. B 108, 054407] Published Mon Aug 07, 2023

**Anisotropy of the spin Hall effect in a Dirac ferromagnet**

Guanxiong Qu, Masamitsu Hayashi, Masao Ogata, and Junji Fujimoto

Author(s): Guanxiong Qu, Masamitsu Hayashi, Masao Ogata, and Junji Fujimoto

[Phys. Rev. B 108, 064404] Published Mon Aug 07, 2023

**Intrinsic and tunable quantum anomalous Hall effect and magnetic topological phases in $XY\mathrm{Bi}{}_{2}\mathrm{Te}{}_{5}$**

Xin-Yi Tang, Zhe Li, Feng Xue, Pengfei Ji, Zetao Zhang, Xiao Feng, Yong Xu, Quansheng Wu, and Ke He

Author(s): Xin-Yi Tang, Zhe Li, Feng Xue, Pengfei Ji, Zetao Zhang, Xiao Feng, Yong Xu, Quansheng Wu, and Ke He

[Phys. Rev. B 108, 075117] Published Mon Aug 07, 2023

**Energy-valley-dependent charge transfer in few-layer transition metal dichalcogenide heterostructures**

Pavel Valencia-Acuna, Stephanie Amos, Hartwin Peelaers, and Hui Zhao

Author(s): Pavel Valencia-Acuna, Stephanie Amos, Hartwin Peelaers, and Hui Zhao

[Phys. Rev. B 108, 085302] Published Mon Aug 07, 2023

**Crystal structure and electrical and optical properties of two-dimensional group-IV monochalcogenides**

Mateus B. P. Querne, Jean M. Bracht, Juarez L. F. Da Silva, Anderson Janotti, and Matheus P. Lima

Author(s): Mateus B. P. Querne, Jean M. Bracht, Juarez L. F. Da Silva, Anderson Janotti, and Matheus P. Lima*ab initio* simulations based on the densit…

[Phys. Rev. B 108, 085409] Published Mon Aug 07, 2023

**Half-quantum flux in spin-triplet superconducting rings with bias current**

Kazushi Aoyama

Author(s): Kazushi Aoyama

[Phys. Rev. B 108, L060502] Published Mon Aug 07, 2023

Found 4 papers in prl Adiabatic time evolution can be used to prepare a complicated quantum many-body state from one that is easier to synthesize and Trotterization can be used to implement such an evolution digitally. The complex interplay between nonadiabaticity and digitization influences the infidelity of this proces… $^{133}{\mathrm{Ba}}^{+}$ is illuminated by a laser that is far detuned from optical transitions, and the resulting spontaneous Raman scattering rate is measured. The observed scattering rate is lower than previous theoretical estimates. The majority of the discrepancy is explained by a more accurat… Resolving the complete electron scattering dynamics mediated by coherent phonons is crucial for understanding electron-phonon couplings beyond equilibrium. Here we present a time-resolved theoretical investigation on strongly coupled ultrafast electron and phonon dynamics in monolayer ${\mathrm{WSe}… A novel acoustic Su-Schrieffer-Heeger chain with non-Hermitian components displays a non-Hermitian phase transition and reveals new acoustic topological interface states with tunable robust confinement.

Date of feed: Tue, 08 Aug 2023 03:17:09 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]+) **Self-Healing of Trotter Error in Digital Adiabatic State Preparation**

Lucas K. Kovalsky, Fernando A. Calderon-Vargas, Matthew D. Grace, Alicia B. Magann, James B. Larsen, Andrew D. Baczewski, and Mohan Sarovar

Author(s): Lucas K. Kovalsky, Fernando A. Calderon-Vargas, Matthew D. Grace, Alicia B. Magann, James B. Larsen, Andrew D. Baczewski, and Mohan Sarovar

[Phys. Rev. Lett. 131, 060602] Published Mon Aug 07, 2023

**Raman Scattering Errors in Stimulated-Raman-Induced Logic Gates in $^{133}{\mathrm{Ba}}^{+}$**

Matthew J. Boguslawski, Zachary J. Wall, Samuel R. Vizvary, Isam Daniel Moore, Michael Bareian, David T. C. Allcock, David J. Wineland, Eric R. Hudson, and Wesley C. Campbell

Author(s): Matthew J. Boguslawski, Zachary J. Wall, Samuel R. Vizvary, Isam Daniel Moore, Michael Bareian, David T. C. Allcock, David J. Wineland, Eric R. Hudson, and Wesley C. Campbell

[Phys. Rev. Lett. 131, 063001] Published Mon Aug 07, 2023

**Coherent-Phonon-Driven Intervalley Scattering and Rabi Oscillation in Multivalley 2D Materials**

Chenyu Wang, Xinbao Liu, Qing Chen, Daqiang Chen, Yaxian Wang, and Sheng Meng

Author(s): Chenyu Wang, Xinbao Liu, Qing Chen, Daqiang Chen, Yaxian Wang, and Sheng Meng

[Phys. Rev. Lett. 131, 066401] Published Mon Aug 07, 2023

**Anti-Parity-Time Symmetry in a Su-Schrieffer-Heeger Sonic Lattice**

Bolun Hu, Zhiwang Zhang, Zichong Yue, Danwei Liao, Yimin Liu, Haixiao Zhang, Ying Cheng, Xiaojun Liu, and Johan Christensen

Author(s): Bolun Hu, Zhiwang Zhang, Zichong Yue, Danwei Liao, Yimin Liu, Haixiao Zhang, Ying Cheng, Xiaojun Liu, and Johan Christensen

[Phys. Rev. Lett. 131, 066601] Published Mon Aug 07, 2023

Found 1 papers in prx Experiments on twisted double bilayer graphene reveal the ferromagnetic long-range order and various first-order quantum phase transitions between different broken symmetry states.

Date of feed: Tue, 08 Aug 2023 03:17:09 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]+) **Observation of First-Order Quantum Phase Transitions and Ferromagnetism in Twisted Double Bilayer Graphene**

Le Liu, Xin Lu, Yanbang Chu, Guang Yang, Yalong Yuan, Fanfan Wu, Yiru Ji, Jinpeng Tian, Kenji Watanabe, Takashi Taniguchi, Luojun Du, Dongxia Shi, Jianpeng Liu, Jie Shen, Li Lu, Wei Yang, and Guangyu Zhang

Author(s): Le Liu, Xin Lu, Yanbang Chu, Guang Yang, Yalong Yuan, Fanfan Wu, Yiru Ji, Jinpeng Tian, Kenji Watanabe, Takashi Taniguchi, Luojun Du, Dongxia Shi, Jianpeng Liu, Jie Shen, Li Lu, Wei Yang, and Guangyu Zhang

[Phys. Rev. X 13, 031015] Published Mon Aug 07, 2023

Found 1 papers in nat-comm **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]+) **Interplay of structure and photophysics of individualized rod-shaped graphene quantum dots with up to 132 sp² carbon atoms**

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Found 1 papers in comm-phys Communications Physics, Published online: 07 August 2023; doi:10.1038/s42005-023-01328-4**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]+) **Chiral and helical states in selective-area epitaxial heterostructure**

Qing Lin He