Found 58 papers in cond-mat Magnons serve as a testing ground for fundamental aspects of Hermitian and
non-Hermitian wave mechanics and are of high relevance for information
technology. This study presents setups for realizing spatio-temporally driven
parity-time (PT) symmetric magnonics based on coupled magnetic waveguides and
magnonic crystals. A charge current in a metal layer with strong spin-orbit
coupling sandwiched between two insulating magnetic waveguides leads to gain or
loss in the magnon amplitude depending on the directions of the magnetization
and the charge currents. When gain in one waveguide is balanced by loss in the
other waveguide a PT-symmetric system hosting non-Hermitian degeneracies (or
exceptional points (EPs)) is realized. For AC current multiple EPs appear for a
certain gain/loss strength and mark the boundaries between the preserved
PT-symmetry and the broken PT-symmetry phases. The number of islands of broken
PT-symmetry phases and their extensions is tunable by the frequency and the
strength of the spacer current. At EP and beyond, the induced and amplified
magnetization oscillations are strong and self-sustained. In particular, these
magnetization auto-oscillations in broken PT-symmetry phase occur at low
current densities and do not require further adjustments such as tilt angle
between electric polarization and equilibrium magnetization direction in
spin-torque oscillators, pointing to a new design of these oscillators and
their utilization in computing and sensoric. It is also shown how the periodic
gain/loss mechanism allows for the generation of high-frequency spin waves with
low-frequency currents. For spatially-periodic gain/loss acting on a magnonic
crystal, magnon modes approaching each other at the Brillouin-zone boundaries
are highly susceptible to PT-symmetry, allowing for a wave-vector-resolved
experimental realization at very low currents.
The experimental results hinting at the room temperature and ambient pressure
superconductivity and magnetic levitation in LK-99 attracted an unprecedented
interest. While attempts of other teams to reproduce the reported observations
on similar samples failed so far, it seems worthwhile to try building a
theoretical model that would explain the ensemble of the available data. One of
important features that needs to be explained is an apparent contradiction
between an extremely high critical temperature Tc and rather modest critical
magnetic field Bc and critical current jc reported for LK-99. We show
theoretically, that these data may be quantitatively reproduced assuming the
interplay between exciton- and phonon-induced superconductivity, while the
conventional BCS or Brinkman-Rice-Bardeen-Cooper-Schriefer (BR-BCS) mechanisms
would result in a much higher Bc for the same Tc.
We study the impact of spin-orbit coupling on the topological band-properties
of copper-substituted lead phosphate apatite using a combination of
group-theoretical analysis and full-relativistic density-functional theory
calculations. We characterize Weyl points at time-reversal invariant momenta
and find that a band-inversion due to spin-orbit coupling leads to additional
Weyl points close to the Fermi-edge at general momenta. To determine the
position of the altogether 66 Weyl points in the Brilouin-zone, we develop an
algorithm that follows a Berry-curvature-derived vector field to its monopole:
the Weyl point. The emerging surface Fermi-arcs and their spin-polarization
reveal avoided crossings and a Fermi-loop detached from the Weyl points.
At low temperatures, the interaction of a nanoscale magnet with a Fermi gas
can give rise to the Kondo effect. This is signaled by a zero-bias resonance
with a characteristic temperature evolution of its linewidth. In order to prove
the Kondo nature of the zero-bias peak and to determine the Kondo temperature
in scanning tunneling spectroscopy (STS), the extrinsic contributions to the
measured linewidth have to be properly taken into account. In this paper, by
combination of precise STS measurements of an ideal spin-1/2 Kondo system,
phenalenyl on Au(111), and by theoretical considerations, we show how to
efficiently extract accurate intrinsic Kondo linewidths from finite-temperature
STS measurements. The extracted linewidths fit very well with a recently
derived expression for the intrinsic Kondo linewidth as a function of
temperature, thus proving the validity of the theory. Finally, we show that the
developed methodology allows to reliably extract the intrinsic Kondo width from
a single spectrum measured at finite temperature, thus considerably reducing
the experimental effort.
The intrinsic anomalous Hall effect (AHE) has been reported in numerous
ferromagnetic (FM) Weyl semimetals. However, AHE in the antiferromagnetic (AFM)
or paramagnetic (PM) state of Weyl semimetals has been rarely observed
experimentally, and only in centrosymmetric materials. Different mechanisms
have been proposed to establish the connection between the AHE and the type of
magnetic order. In this paper, we report AHE in both the AFM and PM states of
non-centrosymmetric compound SmAlSi. To account for the AHE in
non-centrosymmetric Weyl semimetals without FM, we introduce a new mechanism
based on magnetic field-induced Weyl nodes evolution. Angle-dependent quantum
oscillations in SmAlSi provide evidence for the Weyl points and large AHE in
both the PM and the AFM states. The proposed mechanism qualitatively explains
the temperature dependence of the anomalous Hall conductivity (AHC), which
displays unconventional power law behavior of the AHC in both AFM and PM states
of SmAlSi.
Transition metal dichalcogenides are investigated for various applications at
the nanoscale thanks to their unique combination of properties and
dimensionality. For many of the anticipated applications, heat conduction plays
an important role. At the same time, these materials often contain relatively
large amounts of point defects. Here, we provide a systematic analysis of the
impact of intrinsic and selected extrinsic defects on the lattice thermal
conductivity of MoS$_2$ and WS$_2$ monolayers. We combine Boltzmann transport
theory and the Green's function-based T-matrix approach for the calculation of
scattering rates. The force constants for the defect configurations are
obtained from density functional theory calculations via a regression approach,
which allows us to sample a rather large number of defects at a moderate
computational cost and to systematically enforce both the translational and
rotational acoustic sum rules. The calculated lattice thermal conductivity is
in quantitative agreement with experimental data for heat transport and defect
concentrations for both MoS$_2$ and WS$_2$. Crucially, this demonstrates that
the strong deviation from a 1/T-temperature dependence of the lattice thermal
conductivity observed experimentally, can be fully explained by the presence of
point defects. We furthermore predict the scattering strengths of the intrinsic
defects to decrease in the sequence $V_{Mo}\approx
V_{2S}^=>V_{2S}^\perp>V_S>S_{ad}$ in both materials, while the scattering rates
for the extrinsic (adatom) defects decrease with increasing mass such that
Li$_{ad}$>Na$_{ad}$>K$_{ad}$. Compared to earlier work, we find that both
intrinsic and extrinsic adatoms are relatively weak scatterers. We attribute
this difference to the treatment of the translational and rotational acoustic
sum rules, which if not enforced can lead to spurious contributions in the
zero-frequency limit.
Topological order offers possibilities for processing quantum information
which can be immune to imperfections. However, the question of its stability
out of equilibrium is relevant for experiments, where coupling to an
environment is unavoidable. In this work we demonstrate the robustness of
certain aspects of $Z_2 \times Z_2$ symmetry-protected topological (SPT) order
against a wide class of dissipation channels in the Lindblad and quantum
trajectory formalisms of an open quantum system. This is illustrated using the
one-dimensional $ZXZ$ cluster Hamiltonian along with Pauli-string jump
operators. We show that certain choices of dissipation retaining strong
symmetries support a steady-state manifold consisting of two non-local logical
qubits, and for Hamiltonian perturbations preserving the global symmetry, the
manifold remains long-lived. In contrast, this metastability is destroyed upon
breaking the above-mentioned symmetry. While the localized edge qubits of the
cluster Hamiltonian are not conserved by the Lindbladian evolution, they do
correspond to weak symmetries and thus retain a memory of their initial state
at all times in the quantum trajectories. We utilize this feature to construct
protocols to retrieve the quantum information either by monitoring jumps or
error mitigation. Our work thus proposes a novel framework to study the
dynamics of dissipative SPT phases and opens the possibility of engineering
entangled states relevant to quantum information processing.
We study the effect of Haldane flux in bilayer $\alpha-\mathcal{T}_3$ lattice
system for possible non-equivalent, commensurate stacking configurations with
tight-binding formalism. Bilayer $\alpha-\mathcal{T}_3$ lattice has six
sublattices in a unit cell and its spectrum comprises six bands.
In the absence of Haldane flux, there are threefold band-crossings at the two
Dirac points for both valance and conduction bands. Introduction of Haldane
flux in a cyclically stacked bilayer $\alpha-\mathcal{T}_3$ lattice system
makes all six bands including two low-energy corrugated partial-flat bands
separated and each band possesses non-zero Chern numbers, making the system
topological.
It is shown that the topological evolution can be incorporated by modifying
the hopping strength between sublattice $B$ and $C$ along all three directions,
keeping those between $A$ and $B$ sublattices unchanged, or in other words,
changing the parameter $\alpha$ in each layer.
In the dice lattice limit of the Chern-insulating phase, the Chern numbers of
the three pairs of bands from low energy to higher energies are $\pm 2$, $\pm
3$, and $\pm 1$. Continuous change of parameter $\alpha$ invokes a phase
transition through a band crossing between the two lower energy bands, at
different values for conduction and valance bands, which further depend on the
next nearest neighbor (NNN) hopping strength.
The Chern numbers of the two lower conduction and valance bands
discontinuously change from $\pm2$ to $\pm 6$, $\pm 3$ to $0$ at the transition
point, leaving the Chern number of the third band intact
Some topological lattice models in two spatial dimensions have been found to
exhibit intricate system size dependence in their ground state degeneracy
(GSD), often known as UV/IR mixing. We distinguish between two explanations for
this phenomenon by explicitly calculating the topological entanglement entropy
(TEE) of a model system, the rank-2 toric code, for a bi-partition of the torus
into two cylinders. Focusing on the fact that the rank-2 toric code is a
translation symmetry-enriched topological phase, we show that viewing distinct
system sizes as different translation symmetry defects can explain both our TEE
results and the GSD of the rank-2 toric code. Our work establishes the symmetry
defect framework as the most complete description of this system size
dependence.
We report terahertz time-domain spectroscopy (TDTS) experiments demonstrating
strong light-matter coupling in a terahertz (THz) LC-metamaterial in which the
phonon resonance of a topological insulator (TI) thin film is coupled to the
photonic modes of an array of electronic split-ring resonators. As we tune the
metamaterial resonance frequency through the frequency of the low frequency
$\alpha$ mode of (Bi$_x$Sb$_{1-x}$)$_2$Te$_3$ (BST), we observe strong mixing
and level repulsion between phonon and metamaterial resonance. This hybrid
resonance is a phonon polariton. We observe a normalized coupling strength,
$\eta$ = $\Omega_R$/$\omega_c$ $\approx$ 0.09, using the measured vacuum Rabi
frequency and cavity resonance. Our results demonstrate that one can tune the
mechanical properties of materials by changing their electromagnetic
environment and therefore modify their magnetic and topological degrees of
freedom via coupling to the lattice in this fashion.
Electrical control of the non-trivial topology in Weyl antiferromagnet is of
great interests to develop next-generation spintronic devices. Recent works
suggest that spin Hall effect can switch the topological antiferromagnetic
order. However, the switching efficiency remains relatively low. Here, we
demonstrate effective manipulation of antiferromagnetic order in Weyl semimetal
Mn3Sn by orbital Hall effect originated from metal Mn or oxide CuOx. While
Mn3Sn is proven to be able to convert orbit current to spin current by itself,
we find that inserting a heavy metal layer like Pt with proper thickness can
effectively reduce the critical switching current density by one order of
magnitude. In addition, we show that the memristor-like switching behavior of
Mn3Sn can mimic the potentiation and depression processes of a synapse with
high linearity, which is beneficial for constructing artificial neural network
with high accuracy. Our work paves an alternative way to manipulate topological
antiferromagnetic order and may inspire more high-performance antiferromagnetic
functional devices.
We analyze the two-body spectrum within the Hofstadter-Hubbard model on a
square lattice through an exact variational ansatz and study the topological
properties of its low-lying two-body bound-state branches. In particular we
discuss how the Hofstadter-Hubbard butterfly of the two-body branches evolves
as a function of onsite interactions and how to efficiently calculate their
Chern numbers using the Fukui-Hatsugai-Suzuki approach. Our numerical results
are fully consistent with the simple picture that appears in the
strong-coupling limit, where the attraction between fermions forms a composite
boson characterized by an effective hopping parameter and an effective
magnetic-flux ratio.
Antiferromagnetic antiperovskites, where magnetically active 3$d$ metal
cations are placed in the octahedral corners of a perovskite structure, are in
the spotlight due to their intertwined magnetic structure and topological
properties. Especially their anomalous Hall conductivity, which can be
controlled by applied strain and/or electric field, makes them highly
attractive in different electronic applications. Here, we present the study and
theoretical understanding of a new antiperovskite compound that can offer
enormous opportunities in a broad set of applications. Using first-principles
calculations, we investigated the structure, lattice dynamics, noncollinear
magnetic ordering, and electronic behavior in the Vanadium-based antiperovskite
V$_3$AuN. We found an antiperovskite structure centered on N similar to the
Mn$_3A$N family as the structural ground state. In such a phase, a
\emph{Pm$\bar{3}$m} ground state was found in contrast to the \emph{Cmcm}
post-antiperovskite layered structure, as in the V$_3A$N, $A$ = Ga, Ge, As, and
P. We studied the lattice dynamics and electronic properties, demonstrating its
vibrational stability in the cubic structure and a chiral antiferromagnetic
noncollinear ordering as a magnetic ground state. Finally, we found that the
anomalous Hall conductivity, associated with the topological features induced
by the magnetic symmetry, is $\sigma_{xy}$ = $-$291 S$\cdot$cm$^{-1}$
($\sigma_{111}$ = $-$504 S$\cdot$cm$^{-1}$). The latter is the largest reported
in the antiferromagnetic antiperovskite family of compounds.
Using the tight-binding model, we report a gap opening in the energy spectrum
of the twisted bilayer graphene under the application of pressure, that can be
further amplified by the presence of a perpendicular bias voltage. The valley
edges are located along the K-Gamma path of the superlattice Brillouin Zone,
with the bandgap reaching values up to 200 meV in the single-particle picture.
Employing the formalism of the semiconductor Bloch equations, we observe an
enhancement of the bandgap due to the electron-electron interaction, with a
renormalization of the bandgap of about 160 meV. From the solution of the
corresponding Bethe-Salpeter equation, we show that this system supports highly
anisotropic bright excitons whose electrons and holes are strongly hybridized
between the adjacent layers.
Nonlinear optical (NLO) responses have garnered tremendous interest for
decades due to their fundamental and technological interests. The theory and
calculations of NLO responses including electron-hole interactions, which is
especially crucial for reduced-dimensional materials, however, remain
underdeveloped. Here, we develop an ab initio approach to calculate
second-order nonlinear responses (such as second harmonic generation (SHG) and
shift current) with excitonic effects in an exciton-state basis, going beyond
the independent-particle approximation. We compute SHG in monolayer h-BN and
MoS2 employing exciton states from GW-Bethe-Salpeter equation (GW-BSE)
calculations and show both materials exhibit huge excitonic enhancement. The
physical origin of the enhancement is directly understood through the coupling
amplitudes among exciton states, assisted with diagrammatic representations.
Our method provides an accurate and ab initio description of second-order NLO
responses, capturing self-energy and electron-hole interaction effects.
Holes in silicon quantum dots are promising for spin qubit applications due
to the strong intrinsic spin-orbit coupling. The spin-orbit coupling produces
complex hole-spin dynamics, providing opportunities to further optimize spin
qubits. Here, we demonstrate a singlet-triplet qubit using hole states in a
planar metal-oxide-semiconductor double quantum dot. We observe rapid qubit
control with singlet-triplet oscillations up to 400 MHz. The qubit exhibits
promising coherence, with a maximum dephasing time of 600 ns, which is enhanced
to 1.3 us using refocusing techniques. We investigate the magnetic field
anisotropy of the eigenstates, and determine a magnetic field orientation to
improve the qubit initialisation fidelity. These results present a step forward
for spin qubit technology, by implementing a high quality singlet-triplet
hole-spin qubit in planar architecture suitable for scaling up to 2D arrays of
coupled qubits.
We propose and analyze the terahertz (THz) bolometric vector detectors based
on the graphene-channel field-effect transistors (GC-FET) with the black-P gate
barrier layer or with the composite b-BN/black-P/b-BN gate layer. The phase
difference between the signal received by the FET source and drain
substantially affects the plasmonic resonances. This results in a resonant
variation of the detector response on the incoming THz signal phase shift and
the THz radiation angle of incidence.
We investigate how topological Chern numbers can be defined when
single-particle states hybridize with continua. We do so exemplarily in a
bosonic Haldane model at zero temperature modified by an additional on-site
decay of one boson into two and the conjugate fusion of two bosons into one.
Restricting the Hilbert space to two bosons at maximum, the exact self-energy
is accessible. We use the bilinear Hamiltonian $H_0$ corrected by the
self-energy $\Sigma$ to compute Chern numbers by two different approaches. The
results are gauged against a full many-body calculation in the restricted
Hilbert space. We find evidence that the effective Hamiltonian $H_0(\vec k)
+\Sigma(\omega,\vec k)$ reproduces the correct many-body topology even if the
considered band overlaps with the continuum. However, in the latter case the
bulk-boundary correspondence appears to be no longer valid and the edge modes
delocalize.
Nonlinear transport enabled by symmetry breaking in quantum materials has
aroused considerable interests in condensed matter physics and
interdisciplinary electronics. However, the nonlinear optical response in
centrosymmetric Dirac semimetals via the defect engineering has remained
extremely challenging. Here, we observe the helicity-dependent terahertz (THz)
emission in Dirac semimetal PtTe2 thin films via circular photogalvanic effect
(CPGE) under normal incidence. This is activated by artificially controllable
Te-vacancy defect gradient, which is unambiguously evidenced by the electron
ptychography. The defect gradient lowers the symmetry, which not only induces
the band spin splitting, but also generates the Berry curvature dipole (BCD)
responsible for the CPGE. Such BCD-induced helicity-dependent THz emission can
be manipulated by the Te-vacancy defect concentration. Furthermore, temperature
evolution of the THz emission features the minimum of the THz amplitude due to
the carrier compensation. Our work provides a universal strategy for symmetry
breaking in centrosymmetric Dirac materials for nonlinear transport and
facilitates the promising device applications in integrated optoelectronics and
spintronics.
The topological effects of phonons have been extensively studied in various
materials, particularly in the wide-bandgap semiconductor GaN, which has the
potential to improve heat dissipation in power electronics due to its
intrinsic, topologically-protected, non-dissipative phonon surface states.
Nevertheless, the phase transition of the Weyl phonons in nitrides and their
composite alloys has yet to be elucidated. To unveil the microscale origin,
topological phonon properties in AlGaN alloys are investigated using the
virtual crystal approximation (VCA) and special quasi-random structure (SQS)
approaches in this work. It is found that phase transitions in Weyl phonons are
evidently present in AlGaN alloys and nitride single crystals. Under strain
states, both GaN and AlN show a more prominent phase transition of Weyl phonons
when subjected to biaxial compressive and uniaxial tensile strains. And it has
been observed that the zz components in the self-term and the transverse 1NN
force constants (FCs) are the most influential during the phase transition. The
nonlinear Weyl phonon transition in AlGaN alloys, as modeled by the VCA, is
reflected in the normalized self-term and first-nearest-neighbor (1NN) FCs,
which vary in a nonlinear fashion with an increasing magnitude. This nonlinear
phenomenon is also confirmed in the SQS modeling, where the unfolded phonon
dispersions are consistent with those in the VCA modeling. With increased
branches, hundreds of Weyl phonons are present accompanied by significant
disorders in normalized FCs, which mainly occur for N atoms in self-terms and
for all components in normalized 1NN FCs.
In this study, we investigate both experimentally and computationally the
molecular interactions of two distinct polymers with graphene. Our experimental
findings indicate that the use of a polymer mixture reduces the transfer
induced doping and strain in fabricated graphene devices as compared to
conventional single polymer wet transfer. We found that such reduction is
related to the decreased affinity of mixture of polymethyl methacrylate and
angelica lactone polymer for graphene. We investigated changes in binding
energy (BE) of polymer mixture and graphene by considering energy decomposition
analysis using a pre-trained potential neural network. It was found that
numerical simulations accurately predicted two-fold reduction of BE and order
of magnitude reduction of electrostatic interaction between polymers.
It has been established that the Coulomb interactions can transform the
electron gas into a viscous fluid. This fluid is realized in a number of
platforms, including graphene and two-dimensional semiconductor
heterostructures. The defining characteristic of the electron fluid is the
formation of layers of charge carriers that are in local thermodynamic
equilibrium, as in classical fluids. In the presence of nonuniformities,
whirlpools and nontrivial flow profiles are formed, which have been directly
imaged in recent experiments. In this paper, we theoretically study the
response of the electron fluid to localized magnetic fields. We find that the
electric current is suppressed by viscous vortices in regions where magnetic
field is sharply varying, causing strong transport signatures. Experimentally,
our considerations are relevant since local magnetic fields can be applied to
the system through implanting adatoms or embedding micromagnets in the
top-gate. Our theory is essential for the characterization and future
applications of electron fluids in hydrodynamic spin transport.
The two-dimensional (2D) spin-1/2 kagome Heisenberg antiferromagnet is
believed to host quantum spin liquid (QSL) states with no magnetic order, but
its ground state remains largely elusive. An important outstanding question
concerns the presence or absence of the 1/9 magnetization plateau, where exotic
quantum states, including topological ones, are expected to emerge. Here we
report the magnetization of a recently discovered kagome QSL candidate
YCu$_3$(OH)$_{6.5}$Br$_{2.5}$ up to 57 T. Above 50 T, a clear magnetization
plateau at 1/3 of the saturation moment of Cu$^{2+}$ ions is observed,
supporting that this material provides an ideal platform for the kagome
Heisenberg antiferromagnet. Remarkably, we found another magnetization plateau
around 20 T, which is attributed to the 1/9 plateau. The temperature dependence
of this plateau reveals the distinct spin gap, whose magnitude estimated by the
plateau width is approximately 10% of the exchange interaction. The observation
of 1/9 and 1/3 plateaus highlights the emergence of novel states in quantum
spin systems.
We report a new member of topological insulator (TI) family i.e.,
Mn$_2$Sb$_2$Te$_5$, which belongs to MnSb$_2$Te$_4$ family and is a sister
compound of Mn$_2$Bi$_2$Te$_5$. An antiferromagnetic layer of (MnTe)$_2$ has
been inserted between quintuple layers of Sb$_2$Te$_3$. The crystal structure
and chemical composition of as grown Mn$_2$Sb$_2$Te$_5$ crystal is
experimentally visualized by single crystal XRD (SCXRD) and field emission
scanning electron microscopy (FESEM). The valence states of individual
constituents i.e., Mn, Sb and Te are ascertained through X ray photo electron
spectroscopy (XPS). Different vibrational modes of Mn$_2$Sb$_2$Te$_5$ are
elucidated through Raman spectroscopy. Temperature-dependent resistivity of
Mn$_2$Sb$_2$Te$_5$ resulted in metallic behaviour of the same with an up-turn
at below around 20K. Further, the magneto-transport R(T) vs H of the same
exhibited negative magneto-resistance (MR) at low temperatures below 20K and
small positive at higher temperatures. The low Temperature -ve MR starts
decreasing at higher fields. The magnetic moment as a function of temperature
at 100Oe and 1kOe showed AFM like down turn cusps at around 20K and 10K. The
isothermal magnetization (MH) showed AFM like loops with some embedded FM/PM
domains at 5K and purely paramagnetic (PM) like at 100K. The studied
Mn$_2$Sb$_2$Te$_5$ clearly exhibited the characteristics of a magnetic TI
(MTI).
The current-dipole conductivity formula for doped three-dimensional Dirac
semimetals is derived by using a modified gauge-invariant tight-binding
approach. In a heavily doped regime, the effective number of charge carriers
$n_{\alpha \alpha}^{\rm eff}$ in the Drude contribution is found to be by a
factor of 4 larger than the nominal electron concentration $n$. However, its
structure is the same as in standard Fermi liquid theory. In a lightly doped
regime, on the other hand, the ratio $n_{\alpha \alpha}^{\rm eff}/n$ is much
larger, with much more complex structure of $n_{\alpha \alpha}^{\rm eff}$. It
is shown that the dc resistivity and reflectivity date measured in two TlBiSSe
samples can be easily understood, even in the relaxation-time approximation,
provided that finite quasiparticle lifetime effects in the momentum
distribution functions are properly taken into account.
We show that one dimensional (1D) topological superconductivity can be placed
in the context of phenomena associated with strongly correlated electron
systems. Here we propose a system consisting of a one-dimensional chain of
strongly correlated fermions placed on a superconducting (SC) substrate that
exhibits a spin-singlet extended $s$-wave pairing. Strong electron correlation
is shown to transform an extended $s$-wave SC into a topological SC that hosts
Majorana fermions. In contrast to the approaches based on mean-field
treatments, no Zeeman or exchange magnetic field is needed to produce such an
effect.
We determine the phase diagrams of anisotropic Kitaev-Heisenberg models on
the honeycomb lattice using parton mean-field theories based on different
Majorana fermion representations of the $S=1/2$ spin operators. Firstly, we use
a two-dimensional Jordan-Wigner transformation (JWT) involving a semi-infinite
snake string operator. In order to ensure that the fermionized Hamiltonian
remains local we consider the limit of extreme Ising exchange anisotropy in the
Heisenberg sector. Secondly, we use the conventional Kitaev representation in
terms of four Majorana fermions subject to local constraints, which we enforce
through Lagrange multipliers. For both representations we self-consistently
decouple the interaction terms in the bond and magnetization channels and
determine the phase diagrams as a function of the anisotropy of the Kitaev
couplings and the relative strength of the Ising exchange. While both
mean-field theories produce identical phase boundaries for the topological
phase transition between the gapless and gapped Kitaev quantum spin liquids,
the JWT fails to correctly describe the the magnetic instability and
finite-temperature behavior. Our results show that the magnetic phase
transition is first order at low temperatures but becomes continuous above a
certain temperature.
The development of the next generation of optical phase change technologies
for integrated photonic and free-space platforms relies on the availability of
materials that can be switched repeatedly over large volumes and with low
optical losses. In recent years, the antimony-based chalcogenide phase-change
material Sb$_2$Se$_3$ has been identified as particularly promising for a
number of applications owing to good optical transparency in the near-infrared
part of the spectrum and a high refractive index close to silicon. The
crystallization temperature of Sb$_2$Se$_3$ of around 460 K allows switching to
be achieved at moderate energies using optical or electrical control signals
while providing sufficient data retention time for non-volatile storage. Here,
we investigate the parameter space for optical switching of films of
Sb$_2$Se$_3$ for a range of film thicknesses relevant for optical applications.
By identifying optimal switching conditions, we demonstrate endurance of up to
10$^7$ cycles at reversible switching rates of 20 kHz. Our work demonstrates
that the combination of intrinsic film parameters with pumping conditions is
particularly critical for achieving high endurance in optical phase change
applications.
Tailoring nanoparticles composition and morphology is of particular interest
for improving their performance for catalysis. A challenge of this approach is
that the nanoparticles optimized initial structure often changes during use.
Visualizing the three dimensional (3D) structural transformation in situ is
therefore critical, but often prohibitively difficult experimentally. Although
electron tomography provides opportunities for 3D imaging, restrictions in the
tilt range of in situ holders together with electron dose considerations limit
the possibilities for in situ electron tomography studies. Here, we present an
in situ 3D imaging methodology using single particle reconstruction (SPR) that
allows 3D reconstruction of nanoparticles with controlled electron dose and
without tilting the microscope stage. This in situ SPR methodology was employed
to investigate the restructuring and elemental redistribution within a
population of PtNi nanoparticles at elevated temperatures. We further examined
the atomic structure of PtNi and found a heat induced transition from a
disordered to an ordered phase. Changes in structure and elemental distribution
were linked to a loss of catalytic activity in the oxygen reduction reaction.
The in situ SPR methodology employed here could be extended to a wide range of
in situ studies employing not only heating, but gaseous, aqueous or
electrochemical environments to reveal in operando nanoparticle evolution in
3D.
Existence of nontrivial topological phases in a tight binding Haldane-like
model on the depleted Lieb lattice is reported. This two-band model is
formulated by considering the nearest-neighbor, next-nearest-neighbor and
next-next-nearest-neighbor hopping terms along with complex phase which breaks
the time reversal symmetry of this semi-metallic system. Topological feature of
this model is studied along with the presence of sublattice symmetry breaking
staggered onsite energy. Combined effect of these two broken symmetries is
found crucial for an additional transition between nontrivial and trivial
phases. System exhibits two types of phase transitions, say, between two
nontrivial phases and nontrivial to trivial phases. Nonzero Chern numbers,
existence of Hall plateau and symmetry protected edge states confirm the
presence of the nontrivial phases. This two-band system hosts four different
types of phases where two are topological. Additionally topological properties
of stacked bilayer of the depleted Lieb lattices is also studied with similar
Haldane-like Hamiltonian. This four-band system is found to host Chern
insulating phases, with higher values of Chern numbers supported by in-gap edge
states.
An unconventional bosonization approach that employs a modified Fermi-Bose
correspondence is used to obtain the tunneling density of states (TDOS) of
fractional quantum Hall (FQHE) edges in the vicinity of a point contact. The
chiral Luttinger liquid model is generally used to describe FQHE edge
excitations. We introduce a bosonization procedure to study edge state
transport in Laughlin states at filling $\nu = 1/m$ with $m$ odd (single edge
mode) in the presence of a point contact constriction that brings the top and
bottom edges of the sample into close proximity. The unconventional
bosonization involves modifying the Fermi-Bose correspondence to incorporate
backscattering at the point contact, leaving the action of the theory purely
quadratic even in presence of the inhomogeneity. We have shown convincingly in
earlier works that this procedure correctly reproduces the most singular parts
of the Green functions of the system even when mutual forward scattering
between fermions are included. The most singular part of the density-density
correlation function (DDCF) relevant to TDOS calculation is computed using a
generating functional approach. The TDOS for both the electron tunneling as
well as the Laughlin quasiparticle tunneling cases is obtained and is found to
agree with previous results in the literature. For electron tunneling the
well-known universal power laws for TDOS viz. $ \sim \mbox{ }\omega^{ m-1 }$
and for quasi-particle tunneling the power law $ \sim \mbox{ } \omega^{
\frac{1}{m}-1 } $ are both correctly recovered using our unconventional
bosonization scheme. This demonstrates convincingly the utility of the present
method which unlike conventional approaches, does not treat the point-contact
as an afterthought and yet remains solvable so long as only the most singular
parts of the correlation functions are desired.
Weyl-semimetal superstructures with a spiraling position of a pair of Weyl
nodes of opposite chirality can host a chiral-symmetry preserving Fermi-arc
metal state, where the chirality is carried by cylindrical Fermi surfaces,
electron- and hole-like depending on the chirality. The Fermi surfaces nest at
vanishing momentum separation (zero nesting vector) at the
electron-hole-compensation energy because the nesting is topologically
protected by vanishing spatial overlap of any pair of equal-momentum
opposite-chirality states. In this work we show that the nesting and Coulomb
interaction drive a spontaneous chiral symmetry breaking in such a Fermi arc
metal, which leads to a dynamical axion insulator state but without breaking
translational symmetry (no charge-density-wave order) as in a conventional Weyl
semimetal. As for material realization, we discuss magnetically doped
Bi$_2$Se$_3$, for which the Weyl-node positions depend on the order of the
magnetic dopands. In this case, the axionic condensation can itself stabilize a
spiral order of the magnetization, and hence the spiraling node positions, even
if the magnetic interaction is intrinsically ferromagnetic.
Berry curvature is a fundamental element to characterize topological quantum
physics, while a full measurement of Berry curvature in momentum space was not
reported for topological states. Here we achieve two-dimensional Berry
curvature reconstruction in a photonic quantum anomalous Hall system via Hall
transport measurement of a momentum-resolved wave packet. Integrating measured
Berry curvature over the two-dimensional Brillouin zone, we obtain Chern
numbers corresponding to -1 and 0. Further, we identify bulk-boundary
correspondence by measuring topology-linked chiral edge states at the boundary.
The full topological characterization of photonic Chern bands from Berry
curvature, Chern number, and edge transport measurements enables our photonic
system to serve as a versatile platform for further in-depth study of novel
topological physics.
Topological crystalline insulators (TCIs) are classified by topological
invariants defined with respect to the crystalline symmetries of their gapped
bulk. The bulk-boundary correspondence then links the topological properties of
the bulk to robust observables on the edges, e.g., the existence of robust edge
modes or fractional charge. In one dimension, TCIs protected by reflection
symmetry have been realized in a variety of systems where each unit cell has
spatially distributed degrees of freedom (SDoF). However, these realizations of
TCIs face practical challenges stemming from the sensitivity of the resulting
edge modes to variations in edge termination and to the local breaking of the
protective spatial symmetries by inhomogeneity. Here we demonstrate
topologically protected edge states in a mono-atomic, orbital-based TCI that
mitigates both of these issues. By collapsing all SDoF within the unit cell to
a singular point in space, we eliminate the ambiguity in unit cell definition
and hence remove a prominent source of boundary termination variability. The
topological observables are also more tolerant to disorder in the orbital
energies. To validate this concept, we experimentally realize a lattice of
mechanical resonators where each resonator acts as an "atom" that harbors two
key orbital degrees of freedom having opposite reflection parity. Our
measurements of this system provide direct visualization of the
$sp$-hybridization between orbital modes that leads to a non-trivial band
inversion in the bulk. Furthermore, as the spatial width of the resonators is
tuned, one can drive a transition between a topological and trivial phase. In
the future we expect our approach can be extended to realize orbital-based
obstructed atomic insulators and TCIs in higher dimensions.
An experimental study of Landau levels (LLs) in a system of two-dimensional
massless Dirac fermions based on a critical thickness HgTe quantum well has
been carried out. The magnetotransport and the capacitive response have been
investigated simultaneously. It is shown that the formation of Shubnikov-de
Haas (SdH) oscillations associated with odd v filling factors occurs in a
magnetic field whose strength grows monotonically with v. This behavior is
consistent with calculations of the electron spectrum, which predicts a
decrease in cyclotron gaps with increasing v. Oscillations with even filling
factors, corresponding to spin gaps, behave less trivially. First, the SdH
oscillations with filling factors of 4 and higher are resolved in a magnetic
field that is 2-2.5 times smaller than the field required to resolve
neighboring SdH oscillations with odd filling factors of 3 and higher. This
indicates a significant increase in the size of the spin gap caused by an
interface inversion asymmetry (IIA) leading to Dirac cone splitting in a zero
magnetic field. Using the spin splitting value gamma as a fitting parameter, we
obtained the best agreement between experimental data and calculations at
gamma=1.5 meV. Next, spin splitting for the zeroth and first LLs is observed in
2-3 times stronger magnetic fields than for the other levels, indicating an
increase in disorder near the Dirac point, due to the lack of screening.
Uranium ditelluride (UTe$_2$) has attracted recent interest due to its unique
superconducting properties, which include the potential for a topological
odd-parity superconducting state. Recently, ac-calorimetry measurements under
pressure indicate a change in the ground state of UTe$_2$ from superconducting
to antiferromagnetic at 1.4 GPa. Here, we investigate the effect of pressure on
the crystal structure of UTe$_2$ up to 25 GPa at room temperature using x-ray
diffraction. We find that UTe$_2$, which at ambient conditions has an
orthorhombic ($Immm$) structure, transforms to a body-centered tetragonal
($I4/mmm$) structure at 5 GPa in a quasi-hydrostatic neon (Ne) pressure
transmitting medium. In the absence of a pressure-transmitting medium, this
transformation occurs between 5 and 8 GPa. The data were fit with a third-order
Birch-Murnaghan equation of state resulting in values of $B_0$=46.0 $\pm$ 0.6
GPa, $B^{\prime}$=9.3 $\pm$ 0.5 (no pressure medium) and $B_0$=42.5 $\pm$ 2.0
GPa, $B^{\prime}$=9.3 (fixed) (neon pressure medium) for the $Immm$ phase. For
the $I4/mmm$ phase, $B_0$=78.9 $\pm$ 0.5 GPa and $B^{\prime}$=4.2 $\pm$ 0.1 (no
pressure transmitting medium), and $B_0$=70.0 $\pm$ 1.1 GPa and
$B^{\prime}$=4.1 $\pm$ 0.2 (neon pressure medium). The high-pressure tetragonal
phase is retained after decompression to ambient pressure, with approximately
30% remaining after 2 days. We argue that the observed phase transition into a
higher symmetry structure at P~5 GPa (orthorhombic to tetragonal), is
accompanied by an increase in the shortest distance between uranium atoms from
3.6 Angstrom (orthorhombic) to 3.9 Angstrom (tetragonal), which suggests
localization of the 5f electrons, albeit with a 10.7% decrease in volume.
The charge density wave (CDW) is a condensate that often forms in layered
materials. It is known to carry electric current \emph{en masse}, but the
transport mechanism remains poorly understood at the microscopic level. Its
quantum nature is revealed by several lines of evidence. Experiments often show
lack of CDW displacement when biased just below the threshold for nonlinear
transport, indicating the CDW never reaches the critical point for classical
depinning. Quantum behavior is also revealed by oscillations of period $h/2e$
in CDW conductance vs. magnetic flux, sometimes accompanied by telegraph-like
switching, in $\text{TaS}_3$ rings above 77 K. Here we discuss further evidence
for quantum CDW electron transport. We find that, for temperatures ranging from
9 to 474 K, CDW current-voltage plots of three trichalcogenide materials agree
almost precisely with a modified Zener-tunneling curve and with time-correlated
soliton tunneling model simulations. In our model we treat the Schr\"{o}dinger
equation as an emergent classical equation that describes fluidic
Josephson-like coupling of paired electrons between evolving topological
states. We find that an extension of this \lq classically robust' quantum
picture explains both the $h/2e$ magnetoconductance oscillations and switching
behavior in CDW rings. We consider potential applications for thermally robust
quantum information processing systems.
A comprehensive study of the electronic and structural phase transition from
1T` to Td in the bulk Weyl semimetal Mo1-xWxTe2 at different doping
concentrations has been carried out using time-of-flight momentum microscopy
(including circular and linear dichroism), X-ray photoelectron spectroscopy
(XPS), X-ray photoelectron diffraction (XPD), X-ray diffraction (XRD),
angle-resolved Raman spectroscopy, transport measurements, density functional
theory (DFT) and Kikuchi pattern calculations. High-resolution angle-resolved
photoemission spectroscopy (ARPES) at 20 K reveals surface electronic states,
which are indicative of topological Fermi arcs. Their dispersion agrees with
the position of Weyl points predicted by DFT calculations based on the
experimental crystal structure of our samples determined by XRD. Raman
spectroscopy confirms the inversion symmetry breaking for the Td -phase, which
is a necessary condition for the emergence of topological states. Transport
measurements show that increasing the doping concentration from 2 to 9% leads
to an increase in the temperature of the phase transition from 1T` to Td from
230 K to 270 K. Magnetoresistance and longitudinal elastoresistance show
significantly increased values in the Td -phase due to stimulated inter-pocket
electron backscattering. The results demonstrate the close relationship between
electronic properties and elastic deformations in MoTe2.
Quantum criticality within Dirac fermions harbors a plethora of exotic
phenomena, attracting sustained attention in the past decades. Nevertheless,
the nonequilibrium dynamics therein has rarely been studied. To fill in the
gap, we explore the imaginary-time relaxation dynamics in a typical Dirac
quantum criticality belonging to chiral Heisenberg universality class.
Performing large-scale quantum Monte Carlo simulation, we unveil rich
nonequilibrium critical phenomena from different initial states. Particularly,
a new dynamic exponent characterizing the non-stationary evolution in the
short-time state is determined as $\theta=-0.84(4)$, in sharp contrast with the
prevalent belief that $\theta$ is positive as demonstrated in classical cases.
Furthermore, we propose a universal dynamic scaling theory governing the
fruitful nonequilibrium properties in Dirac quantum criticality. Armed with the
scaling theory, we develop a new framework to investigate fermionic quantum
criticality based on short-time dynamics, paving a promising avenue to
fathoming quantum criticality in diverse fermionic systems with high
efficiency.
We report a comprehensive study on the electronic transport properties of
SrZn$_2$Ge$_2$ single crystals. The in-plane electrical resistivity of the
compound exhibits linear temperature dependence for 80 K < T < 300 K, and T^2
dependence below 40 K, consistent with the Fermi liquid behavior. Both the
transverse and longitudinal magnetoresistance exhibit a crossover at critical
field B* from weak-field quadratic-like to high-field unsaturated linear field
dependence at low temperatures (T \leq 50 K). Different interpretations of this
magnetoresistance crossover behavior are presented based on the quantum limit
of Dirac Fermions and the specific topology of the Fermi surface of the
compound. Abrikosov's theory is employed to explain linear behavior of
magnetoresistance at low temperatures. The Hall resistivity data establish
SrZn$_2$Ge$_2$ as a multiband system with contributions from both the electrons
and holes. The Hall coefficient is observed to decrease with increasing
temperature and magnetic field, changing its sign from positive to negative.
The negative Hall coefficient observed at low temperatures in high fields and
at high temperatures over the entire field range suggests that the highly
mobile electron charge carriers dominate the electronic transport. Our
first-principles calculations show that nontrivial topological surface states
exist in SrZn$_2$Ge$_2$ within the bulk gap along the {\Gamma}-M path. Notably,
these surface states extend from the valence to conduction band with their
number varying based on the Sr and Ge termination plane. The Fermi surface of
the compound exhibits a distinct tetragonal petal-like structure, with one open
and several closed surfaces. Overall, these findings offer crucial insights
into the mechanisms underlying the electronic transport of the compound.
The topological properties of quasiparticles, such as skyrmions and vortices,
have the potential to offer extraordinary metastability through topological
protection, and drive motion with minimal electrical current excitation. This
has promising implications for future applications in spintronics. Skyrmions
frequently appear either in lattice form or as separate, isolated
quasiparticles \cite{Tokura21}. Magnetic ferroelectrics, a subset of
multiferroics that exhibit magnetically induced ferroelectricity, possess
intriguing characteristics like magnetic (electric) field-controlled
ferroelectric (magnetic) responses. Previous research based on Landau theory
indicated the potential to stabilize metastable phases in multiferroic barium
hexaferrite \cite{Karpov19}. We have successfully stabilized these meta-stable
phases through magnetic quenching of hexaferrite nanoparticles, leading to the
creation of compelling topological structures. The structural changes in
individual BaFe$_{12}$O$_{19}$ nanocrystals were scrutinized using Bragg
coherent diffractive imaging, granting us insight into the emergent topological
structures in field-quenched multiferroics. Additionally, we explored why these
structures are energetically preferable for the formation of metastable
topological structures.
In a growing number of materials, phonons have been found to generate a
thermal Hall effect, but the underlying mechanism remains unclear. Inspired by
previous studies that revealed the importance of Tb$^{3+}$ ions in generating
the thermal Hall effect of Tb$_{2}$Ti$_{2}$O$_{7}$, we investigated the role of
Tm$^{3+}$ ions in TmVO$_{4}$, a paramagnetic insulator with a different crystal
structure. We observe a negative thermal Hall conductivity in TmVO$_{4}$ with a
magnitude such that the Hall angle, $|\kappa_{xy}$/$\kappa_{xx}|$, is
approximately 1 x 10$^{-3}$ at $H$ = 15 T and $T$ = 20 K, typical for a
phonon-generated thermal Hall effect. In contrast to the negligible
$\kappa_{xy}$ found in Y$_{2}$Ti$_{2}$O$_{7}$, we observe a negative
$\kappa_{xy}$ in YVO$_{4}$ with a Hall angle of magnitude comparable to that of
TmVO$_{4}$. This shows that the Tm$^{3+}$ ions are not essential for the
thermal Hall effect in this family of materials. Interestingly, at an
intermediate Y concentration of 30 % in Tm$_{1-x}$Y$_{x}$VO$_{4}$,
$\kappa_{xy}$ was found to have a positive sign, pointing to the possible
importance of impurities in the thermal Hall effect of phonons.
This is a self-contained and hopefully readable account on the method of
creation and annihilation operators (also known as the Fock space
representation or the "second quantization" formalism) for non-relativistic
quantum mechanics of many particles. Assuming knowledge only on conventional
quantum mechanics in the wave function formalism, we define the creation and
annihilation operators, discuss their properties, and introduce corresponding
representations of states and operators of many-particle systems. As the title
of the note suggests, we cover most topics treated in sections 6.7 and 6.8 of
Feynman's "Statistical Mechanics: A Set of Lectures". As a preliminary, we also
carefully discuss the symmetry of wave functions describing indistinguishable
particles.
We note that all the contents of the present note are completely standard,
and the definitions and the derivations presented here have been known to many.
Although the style of the present note may be slightly more mathematical than
standard physics literatures, we do not try to achieve full mathematical
rigor.(Note to experts: In particular we here DERIVE the (anti)commutation
relations of the creation and annihilation operators, rather than simply
declaring them. In this sense our approach is quite close to that of Feynman's.
But we here focus on the action of creation/annihilation operators on general
$N$ body wave functions, while Feynman makes a heavy use of
Slater-determinant-type states from the beginning. We hope that our
presentation provides a better perspective on the formalism.)
We explore a solid state qubit defined on valley isospin of electron confined
in a gate-defined quantum dot created in an area of MoS$_2$/WS$_2$-monolayer
lateral junction. We show that a properly oriented junction with respect to the
monolayer lattice can induce intervalley transitions of electron confined in
the neighboring quantum dot when overlapping with the junction is significant
and pumping frequency tuned. The pumping scheme that induces transitions is
all-electrical: obtained by applying oscillating voltages to control gates and
thus enables for scalable qubit architectures. We also report another
possibility of valley-qubit manipulation by accumulating non-Abelian Berry
phase. To model nanodevice we solve the time-dependent Schr\"odinger equation
in a tight-binding approach and obtain exact time-evolution of the valley-qubit
system. During the evolution we simultaneously solve the Poisson equation in
self-consistent manner with the Schr\"odinger equation, with the confinement
potential controlled via voltages applied to the local gates.
Manipulating quantum states through light-matter interactions has been
actively pursued in two-dimensional (2D) materials research. Significant
progress has been made towards the optical control of the valley degrees of
freedom in semiconducting monolayer transition-metal dichalcogenides (TMD),
based on doubly degenerate excitons from their two distinct valleys in
reciprocal space. Here, we introduce a novel kind of optically controllable
doubly degenerate exciton states that come from a single valley, dubbed as
single-valley exciton doublet (SVXD) states. They are unique in that their
constituent holes originate from the same valence band, making possible the
direct optical control of the spin structure of the excited constituent
electrons. Combining ab initio GW plus Bethe-Salpeter equation (GW-BSE)
calculations and a newly developed theoretical analysis method, we demonstrate
such novel SVXD in substrate-supported monolayer bismuthene -- which has been
successfully grown using molecular beam epitaxy. In each of the two distinct
valleys in the Brillouin zone, strong spin-orbit coupling and $C_{3v}$ symmetry
lead to a pair of degenerate 1s exciton states (the SVXD states) with opposite
spin configurations. Any coherent linear combinations of the SVXD in a single
valley can be excited by light with a specific polarization, enabling full
manipulation of their internal spin configurations. In particular, a
controllable net spin magnetization can be generated through light excitation.
Our findings open new routes to control quantum degrees of freedom, paving the
way for applications in spintronics and quantum information science.
Cell neighbor exchanges play a critical role in regulating tissue fluidity
during epithelial morphogenesis and repair. In vivo, these neighbor exchanges
are often hindered by the formation of transiently stable four-fold vertices,
which can develop into complex multicellular rosettes where five or more cell
junctions meet. Despite their importance, the mechanical origins of
multicellular rosettes have remained elusive, and current cellular models lack
the ability to explain their formation and maintenance. Here we present a
dynamic vertex model of epithelial tissues with strain-dependent tension
remodeling and mechanical memory dissipation. We show that an increase in cell
junction tension upon contraction and reduction in tension upon extension can
stabilize higher-order vertices, temporarily stalling cell rearrangements. On
the other hand, inducing mechanical memory dissipation via relaxation of
junction strain and stress promotes the resolution of higher-order vertices,
facilitating cell neighbor exchanges. We demonstrate that by tuning the rates
of tension remodeling and mechanical memory dissipation, we can control
topological transitions and tissue material properties, recapitulating complex
cellular topologies seen in developing organisms.
The energy structure of an anisotropically interacting Kitaev model on a
honeycomb lattice under triaxial strain is investigated. A numerical
calculation shows that quantized states appear in the low-energy region, even
when the anisotropy of the interaction is rather strong. Their energies are
proportional to the square root of the quantum number and the quantized state
at zero energy appears only on one sublattice. These findings indicate the
emergence of the strain-induced Landau levels of Majorana fermions, which is
also confirmed by an analytical calculation. These Landau levels are stable,
when the direction of triaxial strain is slightly changed from the bond
direction.
Hole-spin qubits in semiconductors represent a mature platform for quantum
technological applications. Here we consider their use as quantum sensors, and
specifically for inferring the presence and estimating the distance from the
qubit of a remote charge. Different approaches are considered - based on the
use of single or double quantum dots, ground and out-of-equilibrium states,
Rabi and Ramsey measurements - and comparatively analyzed by means of the
discrimination probability, and of the classical and quantum Fisher
information. Detailed quantitative aspects result from the multiband character
of the hole states, which we account for by means of the Luttinger-Kohn
Hamiltonian. Furthermore, general conclusions can be drawn on the relative
efficiency of the above options, and analytical expressions are derived for the
Fisher information of a generic qubit within the Rabi and Ramsey schemes.
The interplay between charge order (CO) and nontrivial band topology has
spurred tremendous interest in understanding topological excitations beyond the
single-particle description. In a quasi-one-dimensional nonsymmorphic crystal
TaTe$_4$, the (2a$\times$2b$\times$3c) charge ordered ground state drives the
system into a space group where the symmetry indicator features the emergence
of Dirac fermions and unconventional double Dirac fermions. Using
angle-resolved photoemission spectroscopy and first-principles calculations, we
provide evidence of the CO induced Dirac fermion-related bands near the Fermi
level. Furthermore, the band folding at the Fermi level is compatible with the
new periodicity dictated by the CO, indicating that the electrons near the
Fermi level follow the crystalline symmetries needed to host double Dirac
fermions in this system.
We discuss a two-parameter renormalization group (RG) flow when parameters
are organized in a single complex variable, $\tau$, with modular properties.
Throughout the work we consider a special limit when the imaginary part of
$\tau$ characterizing the disorder strength tends to zero. We argue that
generalized Riemann-Thomae (gRT) function and the corresponding generalized
Devil's staircase emerge naturally in a variety of physical models providing a
universal behavior. In 1D we study the Anderson-like probe hopping in a weakly
disordered lattice, recognize the origin of the gRT function in the spectral
density of the probe and formulate specific RG procedure which gets mapped onto
the discrete flow in the fundamental domain of the modular group $SL(2,Z)$. In
2D we consider the generalization of the phyllotaxis crystal model proposed by
L. Levitov and suggest the explicit form of the effective potential for the
probe particle propagating in the symmetric and asymmetric 2D lattice of
defects. Analyzing the structure of RG flow equations in the vicinity of saddle
points we claim emergence of BKT-like transitions at ${\rm Im}\,\tau\to 0$. We
show that the RG-like dynamics in the fundamental domain of $SL(2,Z)$ for
asymmetric lattices asymptotically approaches the "Silver ratio". For a Hubbard
model of particles on a ring interacting via long-ranged potentials we
investigate the dependence of the ground state energy on the potential and
demonstrate by combining numerical and analytical tools the emergence of the
generalized Devil's staircase. Also we conjecture a bridge between a Hubbard
model and a phyllotaxis.
Antiferromagnets (AFMs) are promising materials for future high-frequency
field-free spintronic applications. Self-localized spin structures can enhance
their capabilities and introduce new functionalities to AFM-based devices. Here
we consider a domain wall (DW), a topological soliton that bridges a connection
between two ground states, similar to a Josephson junction (JJ) link between
two superconductors. We demonstrate the similarities between DWs in bi-axial
AFM with easy-axis primary anisotropy, driven by a spin current, and long
Josephson junctions (LJJs). We found that the Bloch line (BL) in DWs resembles
the fluxon state of JJs, creating a close analogy between the two systems. We
propose a scheme that allows us to create, move, read, and delete such BLs.
This transmission line operates at room temperature and can be dynamically
reconfigured in contrast to superconductors. Results of a developed model were
confirmed by micromagnetic simulations for Cr$_2$O$_3$ and DyFeO$_3$, i.e.,
correspondingly with weak and strong in-plane anisotropy. Overall, the proposed
scheme has significant potential for use in magnetic memory and logic devices.
Two-dimensional electron systems offer an appealing platform to explore
long-lived excitations arising due to collinear carrier scattering enabled by
phase-space constraints at the Fermi surface. Recently it was found that these
effects can boost excitation lifetimes over the fundamental bound set by
Landau's Fermi-liquid theory by a factor as large as $(T_F/T)^\alpha$ with
$\alpha\approx 2$. Long-lived degrees of freedom possess the capability to
amplify the response to weak perturbations, producing lasting collective memory
effects. This leads to non-Newtonian hydrodynamics in 2D electron fluids driven
by multiple viscous modes with scale-dependent viscosity. We describe these
modes as Fermi surface modulations of odd parity evolving in space and time,
and discuss their implications for experimental studies of electron
hydrodynamics.
Consider a d-dimensional quantum field theory (QFT) $\mathfrak{T}$, with a
generalized symmetry $\mathcal{S}$, which may or may not be invertible. We
study the action of $\mathcal{S}$ on generalized or $q$-charges, i.e.
$q$-dimensional operators. The main result of this paper is that $q$-charges
are characterized in terms of the topological defects of the Symmetry
Topological Field Theory (SymTFT) of $\mathcal{S}$, also known as the
``Sandwich Construction''. The SymTFT is a $(d+1)$-dimensional topological
field theory, which encodes the symmetry $\mathcal{S}$ and the physical theory
in terms of its boundary conditions. Our proposal applies quite generally to
any finite symmetry $\mathcal{S}$, including non-invertible, categorical
symmetries. Mathematically, the topological defects of the SymTFT form the
Drinfeld Center of the symmetry category $\mathcal{S}$. Applied to invertible
symmetries, we recover the result of Part I of this series of papers. After
providing general arguments for the identification of $q$-charges with the
topological defects of the SymTFT, we develop this program in detail for QFTs
in 2d (for general fusion category symmetries) and 3d (for fusion 2-category
symmetries).
Within the method of spectral moments it is possible to construct the
spectral function of a many-electron system from the first $2P$ spectral
moments ($P=1,2,3,\dots$). The case $P=1$ corresponds to standard Kohn-Sham
density functional theory (KS-DFT). Taking $P>1$ allows us to consider
additional important properties of the uniform electron gas (UEG) in the
construction of suitable moment potentials for moment-functional based spectral
density-functional theory (MFbSDFT). For example, the quasiparticle
renormalization factor $Z$, which is not explicitly considered in KS-DFT, can
be included easily. In the 4-pole approximation of the spectral function of the
UEG (corresponding to $P=4$) we can reproduce the momentum distribution, the
second spectral moment, and the charge response acceptably well, while a
treatment of the UEG by KS-DFT reproduces from these properties only the charge
response. For weakly and moderately correlated systems we may reproduce the
most important aspects of the 4-pole approximation by an optimized two-pole
model, which leaves away the low-energy satellite band. From the optimized
two-pole model we extract \textit{parameter-free universal} moment potentials
for MFbSDFT, which improve the description of the bandgaps in Si, SiC, BN, MgO,
CaO, and ZnO significantly.
We study an exactly solvable model with bond-directional quadrupolar and
octupolar interactions between spin-orbital entangled $j_{\mathrm{eff}} =
\frac{3}{2}$ moments on the honeycomb lattice. We show that this model features
a multipolar spin liquid phase with gapless fermionic excitations. In the
presence of perturbations that break time-reversal and rotation symmetries, we
find Abelian and non-Abelian topological phases in which the Chern number
evaluates to $0$, $\pm 1$, and $\pm 2$. We also investigate quantum phase
transitions out of the multipolar spin liquid using a parton mean-field
approach and orbital wave theory. In the regime of strong
integrability-breaking interactions, the multipolar spin liquid gives way to
ferroquadrupolar-vortex and antiferro-octupolar ordered phases that harbor a
hidden spin-$\frac{1}{2}$ Kitaev spin liquid. Our work unveils mechanisms for
unusual multipolar orders and quantum spin liquids in Mott insulators with
strong spin-orbit coupling.
The interplay between chirality and topology nurtures many exotic electronic
properties. For instance, topological chiral semimetals display multifold
chiral fermions that manifest nontrivial topological charge and spin texture.
They are an ideal playground for exploring chirality-driven exotic physical
phenomena. In this work, we reveal a monopole-like orbital-momentum locking
texture on the three-dimensional Fermi surfaces of topological chiral
semimetals with B20 structures (e.g., RhSi and PdGa). This orbital texture
enables a large orbital Hall effect (OHE) and a giant orbital magnetoelectric
(OME) effect in the presence of current flow. Different enantiomers exhibit the
same OHE which can be converted to the spin Hall effect by spin-orbit coupling
in materials. In contrast, the OME effect is chirality-dependent and much
larger than its spin counterpart. Our work reveals the crucial role of orbital
texture for understanding OHE and OME effects in topological chiral semimetals
and paves the path for applications in orbitronics, spintronics, and enantiomer
recognition.
We have investigated the effects of strain on two-dimensional square lattices
and examined the methods for inducing pseudo-magnetic fields. In both the
columnar and staggered $\pi$-flux square lattices, we have found that strain
only modulates Fermi velocities rather than inducing pseudo-magnetic fields.
However, spatially non-uniform on-site potentials (anisotropic hoppings) can
create pseudo-magnetic fields in columnar (staggered) $\pi$-flux square
lattices. On the other hand, we demonstrate that strain does induce
pseudo-magnetic fields in staggered zero-flux square lattices. By breaking a
quarter of the bonds, we clarify that a staggered zero-flux square lattice is
topologically equivalent to a honeycomb lattice and displays pseudo-vector
potentials and pseudo-Landau levels at the Dirac points.
The Quantum Materials group at Indian Institute of Technology Patna is
working on a range of topics relating to nanoelectronics, spintronics, clean
energy and memory design etc. The PI has past experiences of working
extensively with superconducting systems like cuprates [1, 2], ruthanate [3],
pnictide [4, 5], thin film heterostructures [6, 7] etc and magnetic recording
media [8, 9] etc. In this report, we have summarised the ongoing works in our
group. We explored a range of functional materials like two-dimensional
materials, oxides. topological insulators, organic materials etc. using a
combination of experimnetal and computational tools. Some of the useful
highlights are as follows: (a) tuning and control of the magnetic and
electronic state of 2D magentic materials with rapid enhancement in the Curie
temperature, (b) Design and detection of single electron transistor based
nanosensors for the detection of biological species with single molecular
resolution, (c) Observation of non-volatile memory behaviour in the hybrid
structures made of perovskite materials and 2D hybrids. The results offer
useful insight in the design of nanoelectronic architecrures for diverse
applications.

Date of feed: Tue, 17 Oct 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]+)|(flatband)|(flat.{1}band)|(LK.{1}99) **Floquet-engineering the exceptional points in parity-time-symmetric magnonics. (arXiv:2310.09300v1 [cond-mat.mes-hall])**

Xi-guang Wang, Lu-lu Zeng, Guang-hua Guo, Jamal Berakdar

**The interplay between exciton- and phonon-induced superconductivity might explain the phenomena observed in LK-99. (arXiv:2310.09305v1 [cond-mat.supr-con])**

Junhui Cao, Alexey Kavokin

**Weyl points and spin-orbit coupling in copper-substituted lead phosphate apatite. (arXiv:2310.09310v1 [cond-mat.mes-hall])**

Martin Braß, Liang Si, Karten Held

**Accurate Kondo temperature determination of spin-1/2 magnetic impurities. (arXiv:2310.09326v1 [cond-mat.str-el])**

Elia Turco, Markus Aapro, Somesh C. Ganguli, Nils Krane, Robert Drost, Nahual Sobrino, Annika Bernhardt, Michal Juríček, Roman Fasel, Pascal Ruffieux, Peter Liljeroth, David Jacob

**Anomalous Hall effect in the antiferromagnetic Weyl semimetal SmAlSi. (arXiv:2310.09364v1 [cond-mat.mtrl-sci])**

Yuxiang Gao, Shiming Lei, Eleanor M. Clements, Yichen Zhang, Xue-Jian Gao, Songxue Chi, Kam Tuen Law, Ming Yi, Jeffrey W. Lynn, Emilia Morosan

**Quantitative predictions of the thermal conductivity in transition metal dichalcogenides: The impact of point defects in MoS$_2$ and WS$_2$ monolayers. (arXiv:2310.09405v1 [cond-mat.mtrl-sci])**

Srinivisan Mahendran, Jesús Carrete, Andreas Isacsson, Georg K. H. Madsen, Paul Erhart

**Edge modes and symmetry-protected topological states in open quantum systems. (arXiv:2310.09406v1 [quant-ph])**

Dawid Paszko, Dominic C. Rose, Marzena H. Szymańska, Arijeet Pal

**Topological properties of nearly flat bands in $\alpha-\mathcal{T}3$ lattice bilayer. (arXiv:2310.09415v1 [cond-mat.mtrl-sci])**

Puspita Parui, Bheema Lingam Chittari

**Unveiling UV/IR Mixing via Symmetry Defects: A View from Topological Entanglement Entropy. (arXiv:2310.09425v1 [cond-mat.str-el])**

Jintae Kim, Yun-Tak Oh, Daniel Bulmash, Jung Hoon Han

**Coupled metamaterial-phonon terahertz range polaritons in a topological insulator. (arXiv:2310.09481v1 [cond-mat.mes-hall])**

Sirak M. Mekonen, Deepti Jain, Seongshik Oh, N.P. Armitage

**Effective electrical manipulation of topological antiferromagnet by orbital Hall effect. (arXiv:2310.09521v1 [cond-mat.mtrl-sci])**

Zhenyi Zheng, Tao Zeng, Tieyang Zhao, Shu Shi, Lizhu Ren, Tongtong Zhang, Lanxin Jia, Youdi Gu, Rui Xiao, Hengan Zhou, Qihan Zhang, Jiaqi Lu, Guilei Wang, Chao Zhao, Huihui Li, Beng Kang Tay, Jingsheng Chen

**Chern numbers for the two-body Hofstadter-Hubbard butterfly. (arXiv:2310.09565v1 [cond-mat.quant-gas])**

D. C. Alyuruk, M. Iskin

**Chiral magnetism, lattice dynamics, and anomalous Hall conductivity in the novel V$_3$AuN antiferromagnetic antiperovskite. (arXiv:2310.09616v1 [cond-mat.str-el])**

J. M. Duran-Pinilla, Aldo H. Romero, A. C. Garcia-Castro

**Moir\'e excitons in biased twisted bilayer graphene under pressure. (arXiv:2310.09645v1 [cond-mat.mes-hall])**

V. G. M. Duarte, D. R. da Costa, N. M. R. Peres, L. K. Teles, A. J. Chaves

**Excitonic effects in nonlinear optical responses: Exciton-state formalism and first-principles calculations. (arXiv:2310.09674v1 [cond-mat.mtrl-sci])**

Jiawei Ruan, Y.-H. Chan, Steven G. Louie

**A singlet-triplet hole-spin qubit in MOS silicon. (arXiv:2310.09722v1 [cond-mat.mes-hall])**

S. D. Liles, D. J. Halverson, Z. Wang, A. Shamim, R. S. Eggli, I. K. Jin, J. Hillier, K. Kumar, I. Vorreiter, M. Rendell, J. H. Huang, C. C. Escott, F. E. Hudson, W. H. Lim, D. Culcer, A. S. Dzurak, A. R. Hamilton

**Phase- and angle-sensitive terahertz hot-electron bolometric plasmonic detectors based on FETs with graphene channel and composite h-BN/black-P/h-BN gate layer. (arXiv:2310.09741v1 [cond-mat.mes-hall])**

V. Ryzhii, M. S. Shur, M. Ryzhii, V. Mitin, C. Tang, T. Otsuji

**Topological Properties of Single-Particle States Decaying into a Continuum due to Interaction. (arXiv:2310.09957v1 [cond-mat.mes-hall])**

B. Hawashin, J. Sirker, G. S. Uhrig

**Defect-induced helicity-dependent terahertz emission in Dirac semimetal PtTe2 thin films. (arXiv:2310.09989v1 [cond-mat.mtrl-sci])**

Zhongqiang Chen, Hongsong Qiu, Xinjuan Cheng, Jizhe Cui, Zuanming Jin, Da Tian, Ruxin Liu, Xu Zhang, Wei Niu, Liqi Zhou, Tianyu Qiu, Zhe Wang, Yequan Chen, Caihong Zhang, Xiaoxiang Xi, Fengqi Song, Rong Yu, Xuechao Zhai, Biaobing Jin, Rong Zhang, Xuefeng Wang

**Variations of Interatomic Force Constants in the Topological Phonon Phase Transition of AlGaN. (arXiv:2310.09996v1 [cond-mat.mtrl-sci])**

Daosheng Tang

**Optimized nanodevice fabrication using clean transfer of graphene by polymer mixture: Experiments and Neural Network based simulations. (arXiv:2310.10020v1 [physics.app-ph])**

Jared K. Averitt, Sajedeh Pourianejad, Olubunmi Ayodele, Kirby Schmidt, Anthony Trofe, Joseph Starobin, Tetyana Ignatova

**Magnetic response of a two-dimensional viscous electron fluid. (arXiv:2310.10032v1 [cond-mat.mes-hall])**

Aydin Cem Keser, Oleg Sushkov

**Emergent spin-gapped magnetization plateaus in a spin-1/2 perfect kagome antiferromagnet. (arXiv:2310.10069v1 [cond-mat.str-el])**

S. Suetsugu, T. Asaba, Y. Kasahara, Y. Kohsaka, K. Totsuka, B. Li, Y. Zhao, Y. Li, M. Tokunaga, Y. Matsuda

**Growth and characterization of the magnetic topological insulator candidate Mn$_2$Sb$_2$Te$_5$. (arXiv:2310.10163v1 [cond-mat.mtrl-sci])**

Ankush Saxena, V.P.S. Awana (CSIR-NPL, India)

**Optical properties of anisotropic Dirac semimetals. (arXiv:2310.10172v1 [cond-mat.mes-hall])**

I. Kupčić, J. Kordić

**A proposal for realizing Majorana fermions without magnetic field in strongly correlated nanowires. (arXiv:2310.10201v1 [cond-mat.supr-con])**

Kaushal Kumar Kesharpu, Evgenii A. Kochetov, Alvaro Ferraz

**Majorana Fermion Mean-Field Theories of Kitaev Quantum Spin Liquids. (arXiv:2310.10230v1 [cond-mat.str-el])**

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

**Optical switching beyond a million cycles of low-loss phase change material Sb$_2$Se$_3$. (arXiv:2310.10252v1 [physics.optics])**

Daniel Lawson, Sophie Blundell, Martin Ebert, Otto L. Muskens, Ioannis Zeimpekis

**In-Situ Single Particle Reconstruction Reveals 3D Evolution of PtNi Nanocatalysts During Heating. (arXiv:2310.10253v1 [physics.app-ph])**

Yi-Chi Wang, Thomas J A Slater, Gerard M. Leteba, Candace I Lang, Zhong Lin Wang, Sarah J Haigh

**Topological phases of monolayer and bilayer depleted Lieb lattices. (arXiv:2310.10286v1 [cond-mat.mes-hall])**

Arghya Sil, Asim Kumar Ghosh

**Tunneling density of states of fractional quantum Hall edges: an unconventional bosonization approach. (arXiv:2310.10319v1 [cond-mat.mes-hall])**

Nikhil Danny Babu, Girish S. Setlur

**Axionic Instability of Periodic Weyl-Semimetal Superstructures. (arXiv:2310.10345v1 [cond-mat.mes-hall])**

Tommy Li, Maxim Breitkreiz

**Berry Curvature and Bulk-Boundary Correspondence from Transport Measurement for Photonic Chern Bands. (arXiv:2310.10365v1 [quant-ph])**

Chao Chen, Run-Ze Liu, Jizhou Wu, Zu-En Su, Xing Ding, Jian Qin, Lin Wang, Wei-Wei Zhang, Yu He, Xi-Lin Wang, Chao-Yang Lu, Li Li, Barry C. Sanders, Xiong-Jun Liu, Jian-Wei Pan

**A mono-atomic orbital-based 1D topological crystalline insulator. (arXiv:2310.10403v1 [cond-mat.mes-hall])**

Gengming Liu, Violet Workman, Jiho Noh, Yuhao Ma, Taylor L. Hughes, Wladimir A. Benalcazar, Gaurav Bahl

**Spin Splitting and Disorder in HgTe-Based Massless Dirac Fermion Landau Levels. (arXiv:2310.10473v1 [cond-mat.mes-hall])**

D. A. Kozlov, J. Ziegler, N. N. Mikhailov, Z. D. Kvon, D.Weiss

**Metastable phase of UTe$_2$ formed under high pressure above 5 GPa. (arXiv:2310.10491v1 [cond-mat.str-el])**

L. Q. Huston, D. Y. Popov, A. Weiland, M. M. Bordelon, P. F. S. Rosa, R. L. Rowland II, B. L. Scott, G. Shen, C. Park, E. K. Moss, S. M. Thomas, J. D. Thompson, B. T. Sturtevant, E. D. Bauer

**Quantum Transport of Charge Density Wave Electrons in Layered Materials. (arXiv:2310.10512v1 [cond-mat.mes-hall])**

John H. Miller Jr, Martha Y. Suárez-Villagrán, Johnathan O. Sanderson

**Doping-Induced Electronic and Structural Phase Transition in the Bulk Weyl Semimetal Mo1-xWxTe2. (arXiv:2310.10593v1 [cond-mat.mtrl-sci])**

O. Fedchenko, F. K. Diekmann, P. Russmann, M. Kallmayer, L. Odenbreit, S. M. Souliou, M. Frachet, A. Winkelmann, M. Merz, S. V. Chernov, D. Vasilyev, D. Kutnyakhov, O. Tkach, Y. Lytvynenko, K. Medjanik, C. Schlueter, A. Gloskovskii, T. R. F. Peixoto, M. Hoesch, M. Le Tacon, Y. Mokrousov, K. Rossnage, G. Schönhense, H.-J. Elmers

**Nonequilibrium dynamics in Dirac quantum criticality. (arXiv:2310.10601v1 [cond-mat.str-el])**

Yin-Kai Yu, Zhi Zeng, Yu-Rong Shu, Zi-Xiang Li, Shuai Yin

**Electronic Transport and Fermi Surface Topology of Zintl phase Dirac Semimetal SrZn2Ge2. (arXiv:2310.10621v1 [cond-mat.str-el])**

M. K. Hooda (1), A. Chakraborty (1 and 2) S. Roy (3), A. Agarwal (1), P. Mandal (4), S. N. Sarangi (5), D. Samal (5 and 6), V. P. S. Awana (7), Z. Hossain (1) ((1) Department of Physics, Indian Institute of Technology, Kanpur-208016, India, (2) Institute of Physics, Johannes Gutenberg Universität, Staudinger Weg 7, 55128 Mainz, Germany, (3) Vidyasagar Metropolitan College, 39, Sankar Ghosh Lane, Kolkata 700006, India, (4) Department of Condensed Matter and Material Physics, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India, (5) Institute of Physics, Bhubaneswar, Bhubaneswar-751005, India, (6) Homi Bhabha National Institute, Anushakti Nagar, Mumbai 400085, India, (7) CSIR National Physical Laboratory, New Delhi, 110012, India)

**Manipulating Metastability: Quenched Control of Topological Defects in Multiferroics. (arXiv:2310.10630v1 [cond-mat.mtrl-sci])**

Nimish P. Nazirkar, Sowmya Srinivasan, Ross Harder, Edwin Fohtung

**Role of magnetic ions in the thermal Hall effect of the paramagnetic insulator TmVO$_{4}$. (arXiv:2310.10643v1 [cond-mat.mtrl-sci])**

Ashvini Vallipuram, Lu Chen, Emma Campillo, Manel Mezidi, Gaël Grissonnanche, Mark P. Zic, Yuntian Li, Ian R. Fisher, Jordan Baglo, Louis Taillefer

**Introduction to the "second quantization" formalism for non-relativistic quantum mechanics: A possible substitution for Sections 6.7 and 6.8 of Feynman's "Statistical Mechanics". (arXiv:1812.10732v5 [cond-mat.stat-mech] UPDATED)**

Hal Tasaki

**Electrical manipulation of valley-qubit and valley geometric phase in lateral monolayer heterostructures. (arXiv:2209.14445v2 [cond-mat.mes-hall] UPDATED)**

Jarosław Pawłowski, John Eric Tiessen, Rockwell Dax, Junxia Shi

**Optically controlled single-valley exciton doublet states with tunable internal spin structures and spin magnetization generation. (arXiv:2211.03334v2 [cond-mat.mtrl-sci] UPDATED)**

Jiawei Ruan, Zhenglu Li, Chin Shen Ong, Steven G. Louie

**Tension Remodeling Controls Topological Transitions in Epithelial Tissues. (arXiv:2211.05591v2 [physics.bio-ph] UPDATED)**

Fernanda Pérez-Verdugo, Shiladitya Banerjee

**Strain-induced Landau levels of Majorana fermions in an anisotropically interacting Kitaev model on a honeycomb lattice. (arXiv:2301.05330v2 [cond-mat.str-el] UPDATED)**

Takuto Yamada, Sei-ichiro Suga

**Quantum estimation and remote charge sensing with a hole-spin qubit in silicon. (arXiv:2303.07161v3 [cond-mat.mes-hall] UPDATED)**

Gaia Forghieri, Andrea Secchi, Andrea Bertoni, Paolo Bordone, Filippo Troiani

**Charge order induced Dirac pockets in the nonsymmorphic crystal TaTe$_4$. (arXiv:2304.00425v3 [cond-mat.str-el] UPDATED)**

Yichen Zhang, Ruixiang Zhou, Hanlin Wu, Ji Seop Oh, Sheng Li, Jianwei Huang, Jonathan D. Denlinger, Makoto Hashimoto, Donghui Lu, Sung-Kwan Mo, Kevin F. Kelly, Robert J. Birgeneau, Bing Lv, Gang Li, Ming Yi

**Generalized Devil's staircase and RG flows. (arXiv:2304.07640v4 [cond-mat.stat-mech] UPDATED)**

Ana Flack, Alexander Gorsky, Sergei Nechaev

**Antiferromagnetic Bloch line driven by spin current as room-temperature analog of a fluxon in a long Josephson junction. (arXiv:2305.02276v3 [cond-mat.mes-hall] UPDATED)**

R.V. Ovcharov, B.A. Ivanov, J. Åkerman, R. S. Khymyn

**Two-dimensional electron gases as non-Newtonian fluids. (arXiv:2305.02883v3 [cond-mat.str-el] UPDATED)**

Serhii Kryhin, Leonid Levitov

**Generalized Charges, Part II: Non-Invertible Symmetries and the Symmetry TFT. (arXiv:2305.17159v2 [hep-th] UPDATED)**

Lakshya Bhardwaj, Sakura Schafer-Nameki

**Bandgaps of insulators from moment-functional based spectral density-functional theory. (arXiv:2306.06259v3 [cond-mat.str-el] UPDATED)**

Frank Freimuth, Stefan Blügel, Yuriy Mokrousov

**Multipolar spin liquid in an exactly solvable model for $j_\mathrm{eff} = \frac{3}{2}$ moments. (arXiv:2306.08624v2 [cond-mat.str-el] UPDATED)**

Vanuildo S. de Carvalho, Hermann Freire, Rodrigo G. Pereira

**Monopole-like orbital-momentum locking and the induced orbital transport in topological chiral semimetals. (arXiv:2307.02668v2 [cond-mat.mes-hall] UPDATED)**

Qun Yang, Jiewen Xiao, Iñigo Robredo, Maia G. Vergniory, Binghai Yan, Claudia Felser

**Pseudo-magnetic fields in square lattices. (arXiv:2309.00212v2 [cond-mat.mes-hall] UPDATED)**

Junsong Sun, Xingchuan Zhu, Tianyu Liu, Shiping Feng, Huaiming Guo

**Quantum Materials Group Annual Report 2022. (arXiv:2310.00456v2 [cond-mat.mes-hall] UPDATED)**

P. Kumari, S. Rani, S. Kar, T. Mukherjee, S. Majumder, K. Kumari, S. J. Ray

Found 8 papers in prb The spin structure of a Mn triple layer grown pseudomorphically on a W(001) surface is studied using spin-polarized scanning tunneling microscopy (SP-STM) and density functional theory (DFT). In SP-STM images a $\mathrm{c}(4×2)$ superstructure is found. The magnetic origin of this contrast is verifi… We have successfully synthesized single crystals, solved the crystal structure, and studied the magnetic properties of a new family of copper halides $({\mathrm{C}}_{4}{\mathrm{H}}_{14}{\mathrm{N}}_{2}){\mathrm{Cu}}_{2}{X}_{6}$ $(X=\mathrm{Cl},\mathrm{Br})$. These compounds crystallize in an orthorh… This study investigates the predictive capabilities of common density functional theory (DFT) methods (GGA, $\mathrm{GGA}+U$, and $\mathrm{GGA}+U+V$) for determining the transition temperature of antiferromagnetic insulators. We utilize a data set of 29 compounds and derive Heisenberg exchanges base… In this paper, we study the ground-state quantum Fisher information (QFI) in one-dimensional spin-1 models, as witness to multipartite entanglement. The models addressed are the bilinear-biquadratic model, the most general isotropic $\text{SU}(2)$-invariant spin-1 chain, and the $XXZ$ spin-1 chain, … Dzyaloshinskii-Moriya interaction (DMI), the antisymmetric exchange interaction in noncentrosymmetric magnets, is a key ingredient in forming and manipulating the magnetic skyrmion, a promising candidate for next-generation data storage. With the development of non-Hermitian topological phases, the … In this work, we study the generalization of decohered average symmetry-protected topological phases to open quantum systems with a combination of subsystem symmetries and global symmetries. In particular, we provide examples of two types of intrinsic average higher-order topological phases with ave… Recent experiments reported that the magnetic field can drive the Lifshitz transition and one-dimensional (1D) Weyl nodes in the quantum limit of three-dimensional pentatellurides, as they own low carrier densities and can achieve the extreme quantum limit at a low magnetic field. In this paper, we … The robust transport of quantized particles in gap systems through adiabatic cyclic evolution corresponds to dynamical versions of topological insulators, which have recently emerged as a thriving topic. Until now, these connections were thought to be limited to gap systems. Here, we report a mechan…

Date of feed: Tue, 17 Oct 2023 03:17:02 GMT**Search terms: **(topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)|(flatband)|(flat.{1}band)|(LK.{1}99) **Evidence for a conical spin spiral state in the Mn triple layer on W(001): Spin-polarized scanning tunneling microscopy and first-principles calculations**

Paula M. Weber, Tim Drevelow, Jing Qi, Matthias Bode, and Stefan Heinze

Author(s): Paula M. Weber, Tim Drevelow, Jing Qi, Matthias Bode, and Stefan Heinze

[Phys. Rev. B 108, 134419] Published Mon Oct 16, 2023

**Crystal structure and magnetic properties of the spin-$\frac{1}{2}$ frustrated two-leg ladder compounds $({\mathrm{C}}_{4}{\mathrm{H}}_{14}{\mathrm{N}}_{2}){\mathrm{Cu}}_{2}{X}_{6}$ $(X=\mathrm{Cl} \text{and} \mathrm{Br})$**

P. Biswal, S. Guchhait, S. Ghosh, S. N. Sarangi, D. Samal, Diptikanta Swain, Manoranjan Kumar, and R. Nath

Author(s): P. Biswal, S. Guchhait, S. Ghosh, S. N. Sarangi, D. Samal, Diptikanta Swain, Manoranjan Kumar, and R. Nath

[Phys. Rev. B 108, 134420] Published Mon Oct 16, 2023

**Benchmarking density functional theory on the prediction of antiferromagnetic transition temperatures**

Zahra Mosleh and Mojtaba Alaei

Author(s): Zahra Mosleh and Mojtaba Alaei

[Phys. Rev. B 108, 144413] Published Mon Oct 16, 2023

**Quantum Fisher information and multipartite entanglement in spin-1 chains**

Federico Dell'Anna, Sunny Pradhan, Cristian Degli Esposti Boschi, and Elisa Ercolessi

Author(s): Federico Dell'Anna, Sunny Pradhan, Cristian Degli Esposti Boschi, and Elisa Ercolessi

[Phys. Rev. B 108, 144414] Published Mon Oct 16, 2023

**Edge-enhanced negative magnetoresistance in a $\mathrm{W}{\mathrm{Se}}_{2}/\mathrm{F}{\mathrm{e}}_{3}\mathrm{Ge}{\mathrm{Te}}_{2}$ heterostructure**

Xin Liao, Zhen-Cun Pan, Chun-Guang Chu, Tong-Yang Zhao, An-Qi Wang, and Zhi-Min Liao

Author(s): Xin Liao, Zhen-Cun Pan, Chun-Guang Chu, Tong-Yang Zhao, An-Qi Wang, and Zhi-Min Liao

[Phys. Rev. B 108, 144416] Published Mon Oct 16, 2023

**Fractonic higher-order topological phases in open quantum systems**

Jian-Hao Zhang, Ke Ding, Shuo Yang, and Zhen Bi

Author(s): Jian-Hao Zhang, Ke Ding, Shuo Yang, and Zhen Bi

[Phys. Rev. B 108, 155123] Published Mon Oct 16, 2023

**Magnetic field driven Lifshitz transition and one-dimensional Weyl nodes in three-dimensional pentatellurides**

Zhigang Cai and Yi-Xiang Wang

Author(s): Zhigang Cai and Yi-Xiang Wang

[Phys. Rev. B 108, 155202] Published Mon Oct 16, 2023

**Acoustic corner state transfer mapping to synthetic higher-order topological semimetal**

Hui Liu, Haonan Wang, Boyang Xie, Hua Cheng, Zhengyou Liu, and Shuqi Chen

Author(s): Hui Liu, Haonan Wang, Boyang Xie, Hua Cheng, Zhengyou Liu, and Shuqi Chen

[Phys. Rev. B 108, L161104] Published Mon Oct 16, 2023

Found 1 papers in prl Nonlinear scattering of magnons and skyrmions in antiferromagnets leads to a spin Hall effect that emerges from real-space topology.

Date of feed: Tue, 17 Oct 2023 03:17:00 GMT**Search terms: **(topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)|(flatband)|(flat.{1}band)|(LK.{1}99) **Nonlinear Topological Magnon Spin Hall Effect**

Zhejunyu Jin, Xianglong Yao, Zhenyu Wang, H. Y. Yuan, Zhaozhuo Zeng, Weiwei Wang, Yunshan Cao, and Peng Yan

Author(s): Zhejunyu Jin, Xianglong Yao, Zhenyu Wang, H. Y. Yuan, Zhaozhuo Zeng, Weiwei Wang, Yunshan Cao, and Peng Yan

[Phys. Rev. Lett. 131, 166704] Published Mon Oct 16, 2023

Found 2 papers in pr_res Many robust physical phenomena in quantum physics are based on topological invariants arising due to intriguing geometrical properties of quantum states. Prime examples are the integer and fractional quantum Hall effects that demonstrate quantized Hall conductances, associated with topology both in … We report on the first experimental characterization of a gamma-ray spectrometer designed to spectrally resolve high-flux photon beams with energies in the GeV range. The spectrometer has been experimentally characterized using a bremsstrahlung source obtained at the Apollon laser facility during th…

Date of feed: Tue, 17 Oct 2023 03:17:02 GMT**Search terms: **(topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)|(flatband)|(flat.{1}band)|(LK.{1}99) **Fractional transconductance via nonadiabatic topological Cooper pair pumping**

Hannes Weisbrich, Raffael L. Klees, Oded Zilberberg, and Wolfgang Belzig

Author(s): Hannes Weisbrich, Raffael L. Klees, Oded Zilberberg, and Wolfgang Belzig

[Phys. Rev. Research 5, 043045] Published Mon Oct 16, 2023

**Experimental characterization of a single-shot spectrometer for high-flux, GeV-scale gamma-ray beams**

N. Cavanagh, K. Fleck, M. J. V. Streeter, E. Gerstmayr, L. T. Dickson, C. Ballage, R. Cadas, L. Calvin, S. Dobosz Dufrénoy, I. Moulanier, L. Romagnani, O. Vasilovici, A. Whitehead, A. Specka, B. Cros, and G. Sarri

Author(s): N. Cavanagh, K. Fleck, M. J. V. Streeter, E. Gerstmayr, L. T. Dickson, C. Ballage, R. Cadas, L. Calvin, S. Dobosz Dufrénoy, I. Moulanier, L. Romagnani, O. Vasilovici, A. Whitehead, A. Specka, B. Cros, and G. Sarri

[Phys. Rev. Research 5, 043046] Published Mon Oct 16, 2023

Found 3 papers in comm-phys Communications Physics, Published online: 14 October 2023; doi:10.1038/s42005-023-01415-6 Communications Physics, Published online: 13 October 2023; doi:10.1038/s42005-023-01373-z **Search terms: **(topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)|(flatband)|(flat.{1}band)|(LK.{1}99) **Ab-initio simulations of coherent phonon-induced pumping of carriers in zirconium pentatelluride**

Yong-Xin Yao

**Investigating the Cuprates as a platform for high-order Van Hove singularities and flat-band physics**

Arun Bansil

**Spontaneous superconducting diode effect in non-magnetic Nb/Ru/Sr _{2}RuO_{4} topological junctions**

Yoshiteru Maeno

Communications Physics, Published online: 13 October 2023; doi:10.1038/s42005-023-01409-4

Non-reciprocal electronic transport in a superconducting device is known as superconducting diode effect, which has potential for dissipationless electronics and computing. Previously, conventional superconductors have been used. Here, authors present their findings of such an effect in devices based on an unconventional superconductor Sr2RuO4 that may break time reversal symmetry.