Found 28 papers in cond-mat Theoretical investigation of Dirac electrons in electrically modulated
graphene under perpendicular magnetic field B is presented. We have carried out
a detailed study of modulation effect on Dirac electrons, which determine its
electrical transport properties. The periodic potential broadens the Landau
levels (LL), which oscillate with magnetic field B and a comparison made with
two-dimensional electron gas system (2DEGS). We have found the effect of Hall
conductivity on electronic conduction in this system. In addition, we find that
Hall conductivity exhibits Weiss oscillations and Shubnikov de Haas (SdH)
oscillations. The effect of temperature and the period of periodic potential on
these oscillations are studied in this work. Furthermore, an integral quantum
Hall effect in graphene is also discussed.
We use unrestricted Hartree-Fock, density matrix renormalization group, and
variational projected entangled pair state calculations to investigate the
ground state phase diagram of the triangular lattice Hubbard model at "half
doping" relative to single occupancy, i.e. at a filling of $(1\pm \frac{1}{2})$
electrons per site. The electron-doped case has a nested Fermi surface in the
non-interacting limit, and hence a weak-coupling instability towards
density-wave orders whose wavevectors are determined by Fermi surface nesting
conditions. We find that at moderate to strong interaction strengths other
spatially-modulated orders arise, with wavevectors distinct from the nesting
vectors. In particular, we identify a series closely-competing itinerant
long-wavelength magnetically ordered states, yielding to uniform ferromagnetic
order at the largest interaction strengths. For half-hole doping and a similar
range of interaction strengths, our data indicate that magnetic orders are most
likely absent.
Floquet engineering, the nonthermal manipulation of material properties on
ultrafast timescales using strong and time-periodic laser fields, has led to
many intriguing observations in quantum materials. However, recent studies on
high-order harmonic generation from solids reveal exceptionally short dephasing
times for field-dressed quantum states, thereby raising questions about the
feasibility of Floquet engineering under strong-field conditions. In this
study, we employ time- and spectrum-resolved quantum-path interferometry to
investigate the dephasing mechanism of excitons driven by intense terahertz
fields in bulk MoS$_2$. By driving with a photon energy far below the material
bandgap, we observe strong hybridization of exciton excited states, with
resonant transitions to these states leading to phase and amplitude modulations
in interferograms. Our results reveal a field-strength-dependent dephasing rate
of dressed excitons, with exciton dissociation identified as the primary cause
of exciton dephasing under high driving fields. Importantly, we demonstrate
that strong-field-driven excitons can exhibit long dephasing times, supporting
the feasibility of Floquet engineering in strong-field environments. Our study
sheds light on the underlying physics of strong-field-driven exciton
decoherence and underscores the potential for nonthermal manipulation of
quantum materials.
We fabricate a twisted trilayer graphene device with consecutive twist angles
of 1.33 and 1.64 degrees, in which we electrostatically tune the electronic
states from each of the two co-existing moir\'e superlattices and the
interactions between them. When both moir\'e superlattices contribute equally
to electrical transport, we report a new type of inter-moir\'e Hofstadter
butterfly. Its Brown-Zak oscillation corresponds to one of the intermediate
quasicrystal length scales of the reconstructed moir\'e of moir\'e (MoM)
superlattice, shedding new light on emergent physics from competing atomic
orders.
A spectroscopic imaging-scanning tunneling microscope (SI-STM) allows the
atomic scale visualization of surface electronic and magnetic structure of
novel quantum materials with high energy resolution. To achieve the optimal
performance, low vibration facility is required. Here, we describe the design
and the performance of an ultrahigh vacuum STM system supported by a hybrid
vibration isolation system that consists of a pneumatic passive and a
piezoelectric active vibration isolation stages. The STM system is equipped
with a 1K pot cryogenic insert and a 9 Tesla superconducting magnet, capable of
continuous SI-STM measurements for 7 days. A field ion microscopy system is
installed for in situ STM tip treatment. We present the detailed vibrational
noise analysis of the hybrid vibration isolation system and demonstrate the
performance of our STM system by taking high resolution spectroscopic maps and
topographic images on several quantum materials. Our results establish a new
strategy to achieve an effective vibration isolation system for high-resolution
STM and other scanning probe microscopy to investigate the nanoscale quantum
phenomena.
We report efficient spin to charge conversion (SCC) in the topological
insulator (TI) based heterostructure ($BiSbTe_{1.5}Se_{1.5}/Cu/Ni_{80}Fe_{20}$)
by using spin-pumping technique where $BiSbTe_{1.5}Se_{1.5}$ is the TI and
$Ni_{80}Fe_{20}$ is the ferromagnetic layer. The SCC, characterized by inverse
Edelstein effect length ($\lambda_{IEE}$) in the TI material gets altered with
an intervening Copper (Cu) layer and it depends on the interlayer thickness.
The introduction of Cu layer at the interface of TI and ferromagnetic metal
(FM) provides a new degree of freedom for tuning the SCC efficiency of the
topological surface states. The significant enhancement of the measured
spin-pumping voltage and the linewidth of ferromagnetic resonance (FMR)
absorption spectra due to the insertion of Cu layer at the interface indicates
a reduction in spin memory loss at the interface that resulted from the
presence of exchange coupling between the surface states of TI and the local
moments of ferromagnetic metal. The temperature dependence (from 8K to 300K) of
the evaluated $\lambda_{IEE}$ data for all the trilayer systems, TI/Cu/FM with
different Cu thickness confirms the effect of exchange coupling between the TI
and FM layer on the spin to charge conversion efficiency of the topological
surface state.
In light of recent developments demonstrating the impact of cavity vacuum
fields inducing the breakdown of topological protection in the integer quantum
Hall effect, a compelling question arises: what effects might cavity vacuum
fields have on fundamental constants in solid-state systems? In this work we
present an experiment that assesses the possibility of the von Klitzing
constant itself being modified. By employing a Wheatstone bridge, we precisely
measure the difference between the quantized Hall resistance of a
cavity-embedded Hall bar and the resistance standard, achieving an accuracy
down to 1 part in 105 for the lowest Landau level. While our results do not
suggest any deviation that could imply a modified Hall resistance, our work
represents pioneering efforts in exploring the fundamental implications of
vacuum fields in solid-state systems.
By combining the nonconserved spin-flip dynamics driving ferromagnetic
ordering with the conserved Kawasaki-exchange dynamics driving phase
segregation, we perform Monte Carlo simulations of the nearest neighbor Ising
model. Such a set up mimics a system consisting of a binary mixture of
\emph{isomers} which is simultaneously undergoing a segregation and an
\emph{interconversion} reaction among themselves . Here, we study such a system
following a quench from the high-temperature homogeneous phase to a temperature
below the demixing transition. We monitor the growth of domains of both the
\emph{winner}, the \emph{isomer} which survives as the majority and the
\emph{loser}, the \emph{isomer} that perishes. Our results show a strong
interplay of the two dynamics at early times leading to a growth of the average
domain size of both the \emph{winner} and \emph{loser} as $\sim t^{1/7}$,
slower than a purely phase-segregating system. At later times, eventually the
dynamics becomes reaction dominated, and the \emph{winner} exhibits a $\sim
t^{1/2}$ growth, expected for a system with purely nonconserved dynamics. On
the other hand, the \emph{loser} at first show a faster growth, albeit, slower
than the \emph{winner}, and then starts to decay before it almost vanishes.
Further, we estimate the time $\tau_s$ marking the crossover from the
early-time slow growth to the late-time reaction dominated faster growth. As a
function of the reaction probability $p_r$, we observe a power-law scaling
$\tau_s \sim p_r^{-x}$, where $x\approx 1.05$, irrespective of temperature. For
a fixed value of $p_r$ too, $\tau_s$ appears to be independent of temperature.
Various fields, including medical and human interaction robots, gain
advantages from the development of bioinspired soft actuators. Many recently
developed grippers are pneumatics that require external pressure supply
systems, thereby limiting the autonomy of these robots. This necessitates the
development of scalable and efficient on-board pressure generation systems.
While conventional air compression systems are hard to miniaturize,
thermopneumatic systems that joule-heat a transducer material to generate
pressure present a promising alternative. However, the transducer materials of
previously reported thermopneumatic systems demonstrate high heat capacities
and limited surface area resulting in long response times and low operation
frequencies. This study presents a thermopneumatic pressure generator using
aerographene, a highly porous (>99.99 %) network of interconnected graphene
microtubes, as lightweight and low heat capacity transducer material. An
aerographene pressurizer module (AGPM) can pressurize a reservoir of 4.2 cm3 to
about ~140 mbar in 50 ms. Periodic operation of the AGPM for 10 s at 0.66 Hz
can further increase the pressure in the reservoir to ~360 mbar. It is
demonstrated that multiple AGPMs can be operated parallelly or in series for
improved performance. For example, three parallelly operated AGPMs can generate
pressure pulses of ~215 mbar. Connecting AGPMs in series increases the maximum
pressure achievable by the system. It is shown that three AGPMs working in
series can pressurize the reservoir to ~2000 mbar in about 2.5 min. The AGPM's
minimalistic design can be easily adapted to circuit boards, making the concept
a promising fit for the on-board pressure supply of soft robots.
Clusters supported by solid substrates are prime candidates for heterogeneous
catalysis and can be prepared in various ways. While mass-selected soft-landing
methods are often used for the generation of monodisperse particles,
self-assembly typically leads to a range of different cluster sizes. Here we
show by scanning tunneling microscopy measurements that in the initial stages
of growth Mn forms trimers on a close-packed hexagonal Ir surface, providing a
route for self-organized monodisperse cluster formation on an isotropic
metallic surface. For an increasing amount of Mn, first a phase with
reconstructed monolayer islands is formed, until at full coverage a
pseudomorphic Mn phase evolves which is the most densely packed one of the
three different observed Mn phases on Ir(111). The magnetic state of both the
reconstructed islands and the pseudomorphic film is found to be the
prototypical antiferromagnetic N\'eel state with 120{\deg} spin rotation
between all nearest neighbors in the hexagonal layer.
We present a comprehensive approach to characterizing labyrinthine structures
that often emerge as a final steady state in pattern forming systems. We employ
machine learning based pattern recognition techniques to identify the types and
locations of topological defects of the local stripe ordering to augment
conventional Fourier analysis. A pair distribution function analysis of the
topological defects reveals subtle differences between labyrinthine structures
which are beyond the conventional characterization methods. We utilize our
approach to highlight a clear morphological transition between two zero-field
labyrinthine structures in single crystal Bi substituted Yttrium Iron Garnet
films. An energy landscape picture is proposed to understand the athermal
dynamics that governs the observed morphological transition. Our work
demonstrates that machine learning based recognition techniques enable novel
studies of rich and complex labyrinthine type structures universal to many
pattern formation systems.
Graphene nanoribbons (GNRs) are thin strips of graphene with unique
properties due to their structure and nanometric dimensions. They stand out as
basic components for the construction of different types of
nanoelectromechanical systems (NEMS), including some very promising sensors and
pumps. However, various phenomena, such as unintended mechanical vibrations,
can induce undesired electrical currents in these devices. Here, we take a
quantum mechanical approach to analyze how currents induced by fluctuations
(either thermal or of some other kind) in suspended GNRs contribute to the
electric current. In particular, we study the pumping current induced by the
adiabatic variation of the Hamiltonian of the system when a transverse
vibration (flexural mode) of a GNR suspended over a gate is excited. Our
theoretical approach and results provide useful tools and rules of thumb to
understand and control the charge current induced by fluctuations in GNR-based
NEMS, which is important for their applications in nanoscale sensors, pumps,
and energy harvesting devices.
The proximity-effect, a phenomenon whereby materials in close contact
appropriate each others electronic-properties, is widely used in nano-scale
devices to induce electron-correlations at heterostructure interfaces. Layered
group-V transition metal dichalcogenides host charge density waves and are
expected to induce CDWs in a thin proximal 2D metal such as graphene. Thus far,
however, the extremely large density of states of the TMDs compared to graphene
have precluded efforts to unambiguously prove such proximity induced charge
density waves (CDW). Here, using scanning tunneling microscopy (STM) and
spectroscopy (STS), we report the first conclusive evidence of a CDW proximity
effect between graphene and the commensurate CDW in 1T-TaS$_2$ (TaS$_2$ for
brevity). We exploit the Mott gap of 1T-TaS$_2$ to scan the sample at bias
voltages wherein only the graphene layer contributes to the STM topography
scans. Furthermore, we observe that graphene modifies the band structure at the
surface of TaS$_2$, by providing mid-gap carriers and reducing the strength of
electron correlations there. We show that the mechanism underlying the
proximity induced CDW is well-described by short-range exchange interactions
that are distinctly different from previously observed proximity effects.
Anomalous topological phases, where edge states coexist with topologically
trivial Chern bands, can only appear in periodically driven lattices. When the
driving is smooth and continuous, the bulk-edge correspondence is guaranteed by
the existence of a bulk invariant known as the winding number. However, in
lattices subject to periodic time-step walks the existence of edge states does
not only depend on bulk invariants but also on the geometry of the boundary.
This is a consequence of the absence of an intrinsic time-dependence or
micromotion in discrete-step walks. We report the observation of edge states
and a simultaneous measurement of the bulk invariants in anomalous topological
phases in a two-dimensional discrete-step walk in a synthetic photonic lattice
made of two coupled fibre rings. The presence of edge states is inherent to the
periodic driving and depends on the geometry of the boundary in the implemented
two-band model with zero Chern number. We provide a suitable expression for the
topological invariants whose calculation does not rely on micromotion dynamics.
We study the magnon spectrum in skyrmion crystal formed in thin ferromagnetic
films with Dzyalosinskii-Moria interaction in presence of magnetic field.
Focusing on two low-lying observable magnon modes and employing stereographic
projection method, we develop a theory demonstrating a topological transition
in the spectrum. Upon the increase of magnetic field, the gap between two
magnon bands closes, with the ensuing change in the topological character of
both bands. This phenomenon of gap closing, if confirmed in magnetic resonance
experiments, may deserve further investigation by thermal Hall conductivity
experiments.
Effect of an external magnetic field on the critical sound attenuation and
velocity of the longitudinal wave is studied in ferromagnets. We derive a
parametric model that incorporates a crossover from the asymptotic critical
behavior to the Landau-Ginzburg regular behavior far away from the critical
point. The dynamics is based on the time dependent Ginzburg-Landau model with
non conserved order parameter (model A). The variations of the sound
attenuation coefficient and velocity have been obtained for arbitrary values of
the magnetic field and reduced temperature. The scaling functions are given
within the renormalization group formalism at one-loop order. Using MnP as an
example, we show that such parametric crossover model yields an accurate
description of ultrasonic data in a large region of temperatures and magnetic
fields around the critical point.
In cosmology, the axion is a hypothetical particle that is currently
considered as candidate for dark matter. In condensed matter, a counterpart of
the axion (the "axion quasiparticle") has been predicted to emerge in
magnetoelectric insulators with fluctuating magnetic order and in
charge-ordered Weyl semimetals. To date, both the cosmological and
condensed-matter axions remain experimentally elusive or unconfirmed. Here, we
show theoretically that ordinary lattice vibrations can form an axion
quasiparticle in Dirac insulators with broken time- and space-inversion
symmetries, even in the absence of magnetic fluctuations. The physical
manifestation of the phononic axion is a magnetic-field-induced phonon
effective charge, which can be probed in optical spectroscopy. By replacing
magnetic fluctuations with lattice vibrations, our theory widens the scope for
the observability of the axion quasiparticle in condensed matter.
The class of 2D carbon allotropes has garnered significant attention due to
its exceptional optoelectronic and mechanical properties, crucial for diverse
device applications, such as energy storage. This study employs density
functional theory calculations, ab initio molecular dynamics (AIMD), and
classical reactive (ReaxFF) molecular dynamics (MD) simulations to introduce
TODD-Graphene, a novel 2D planar carbon allotrope with a porous structure
composed of 3-8-10-12 carbon rings. TODD-G exhibits intrinsic metallic
properties with low formation energy and demonstrates exceptional dynamic,
thermal, and mechanical stability. Calculations reveal a high theoretical
capacity for adsorbing Li atoms by showing a low average diffusion barrier of
0.83 eV and a metallic framework boasting excellent conductivity, emerging as a
promising anode material for lithium-ion batteries. We also calculated the
charge carrier mobility for electrons and holes in TOOD-G, and the values
surpassed the graphene ones. Classical reactive MD simulation results suggested
its structural integrity with no bond reconstructions at 1800 K.
Long and stable timescales are often observed in complex biochemical
networks, such as in emergent oscillations. How these robust dynamics persist
remains unclear, given the many stochastic reactions and shorter time scales
demonstrated by underlying components. We propose a topological model with
parsimonious parameters that produces long oscillations around the network
boundary, effectively reducing the system dynamics to a lower-dimensional
current. Using this to model KaiC, which regulates the circadian rhythm in
cyanobacteria, we compare the coherence of oscillations to that in other KaiC
models. Our topological model localizes currents on the system edge for an
efficient regime with simultaneously increased precision and decreased cost.
Further, we introduce a new predictor of coherence from the analysis of
spectral gaps, and show that our model saturates a global thermodynamic bound.
Our work presents a new mechanism for emergent oscillations in complex
biological networks utilizing dissipative cycles to achieve robustness and
efficient performance.
We present a numerical study of the transport and localization properties of
excitations in one-dimensional lattices with diagonal disordered mosaic
modulations. The model is characterized by the modulation period $\kappa$ and
the disorder strength $W$. We calculate the disorder averages $\langle
T\rangle$, $\langle \ln T\rangle$, and $\langle P\rangle$, where $T$ is the
transmittance and $P$ is the participation ratio, as a function of energy $E$
and system size $L$, for different values of $\kappa$ and $W$. For excitations
at quasiresonance energies determined by $\kappa$, we find power-law scaling
behaviors of the form $\langle T \rangle \propto L^{-\gamma_{a}}$, $\langle \ln
T \rangle \approx -\gamma_g \ln L$, and $\langle P \rangle \propto L^{\beta}$,
as $L$ increases to a large value. This behavior is in contrast to the
exponential localization behavior occurring at all other energies. The
appearance of sharp peaks in the participation ratio spectrum at quasiresonance
energies provides additional evidence for the existence of an anomalous
power-law localization phenomenon. The corresponding eigenstates demonstrate
multifractal behavior and exhibit unique node structures. In addition, we
investigate the time-dependent wave packet dynamics and calculate the mean
square displacement $\langle m^2(t) \rangle$, spatial probability distribution,
participation number, and return probability. When the wave packet's initial
momentum satisfies the quasiresonance condition, we observe a subdiffusive
spreading of the wave packet, characterized by $\langle m^2(t) \rangle\propto
t^{\eta}$ where $\eta$ is always less than 1. We also note the occurrence of
partial localization at quasiresonance energies, as indicated by the saturation
of the participation number and a nonzero value for the return probability at
long times.
We consider the transverse field Ising model in $(2+1)$D, putting 12 spins at
the vertices of the regular icosahedron. The model is tiny by the exact
diagonalization standards, and breaks rotation invariance. Yet we show that it
allows a meaningful comparison to the 3D Ising CFT on $\mathbb{R}\times S^2$,
by including effective perturbations of the CFT Hamiltonian with a handful of
local operators. This extreme example shows the power of conformal perturbation
theory in understanding finite $N$ effects in models on regularized $S^2$. Its
ideal arena of application should be the recently proposed models of fuzzy
sphere regularization.
This work presents a formalism to derive field quantities and conservation
laws from the atomistic using the theory of distributions as the mathematical
tool. By defining temperature as a derived quantity as that in molecular
kinetic theory and atomistic simulations, a field representation of the
conservation law of linear momentum is derived and expressed in terms of
temperature field, leading to a unified atomistic and continuum description of
temperature and a new conservation equation of linear momentum that,
supplemented by an interatomic potential, completely governs thermal and
mechanical processes across scales from the atomic to the continuum. The
conservation equation can be used to solve atomistic trajectories for systems
at finite temperatures, as well as the evolution of field quantities in space
and time, with atomic or multiscale resolution. Four sets of numerical examples
are presented to demonstrate the efficacy of the formulation in capturing the
effect of temperature or thermal fluctuations, including phonon density of
states, thermally activated dislocation motion, dislocation formation during
epitaxial processes, and attenuation of longitudinal acoustic waves as a result
of their interaction with thermal phonons.
Cell rearrangements are fundamental mechanisms driving large-scale
deformations of living tissues. In three-dimensional (3D) space-filling cell
aggregates, cells rearrange through local topological transitions of the
network of cell-cell interfaces, which is most conveniently described by the
vertex model. Since these transitions are not yet mathematically properly
formulated, the 3D vertex model is generally difficult to implement. The few
existing implementations rely on highly customized and complex
software-engineering solutions, which cannot be transparently delineated and
are thus mostly non-reproducible. To solve this outstanding problem, we propose
a reformulation of the vertex model. Our approach, called Graph Vertex Model
(GVM), is based on storing the topology of the cell network into a knowledge
graph with a particular data structure that allows performing
cell-rearrangement events by simple graph transformations. We find these
transformations consinsting of transformation patterns corresponding to T1
transitions, thereby unifying topological transitions in 2D and 3D
space-filling packings. This result suggests that the GVM's graph data
structure may be the most natural representation of cell aggregates and
tissues. We use GVM to characterize solid-fluid transition in 3D cell
aggregates, driven by active noise and find aggregates undergoing efficient
ordering close to the transition point. In all, our work showcases knowledge
graphs as particularly suitable data models for structured storage, analysis,
and manipulation of tissue data, which potentially has paradigm-shifting
implications for the fields of tissue biophysics and biology.
The concept of \emph{complexity} has become pivotal in multiple disciplines,
including quantum information, where it serves as an alternative metric for
gauging the chaotic evolution of a quantum state. This paper focuses on
\emph{Krylov complexity}, a specialized form of quantum complexity that offers
an unambiguous and intrinsically meaningful assessment of the spread of a
quantum state over all possible orthogonal bases. Our study is situated in the
context of Gaussian quantum states, which are fundamental to both Bosonic and
Fermionic systems and can be fully described by a covariance matrix. We show
that while the covariance matrix is essential, it is insufficient alone for
calculating Krylov complexity due to its lack of relative phase information.
Our findings suggest that the relative covariance matrix can provide an upper
bound for Krylov complexity for Gaussian quantum states. We also explore the
implications of Krylov complexity for theories proposing complexity as a
candidate for holographic duality by computing Krylov complexity for the
thermofield double States (TFD) and Dirac field.
Antimony shows promise as a two-dimensional (2D) mono-elemental crystal,
referred to as antimonene. When exposed to ambient conditions, antimonene
layers react with oxygen, forming new crystal structures, leading significant
changes in electronic properties. These changes are influenced by the degree of
oxidation. Utilizing Density Functional Theory (DFT) calculations, stable
configurations of bilayer antimony oxide and their corresponding electronic
properties are studied. Additionally, different stacking arrangements and their
effects on the physical properties of the materials are investigated.
Furthermore, the analysis encompasses strain-free hetero-bilayers containing
both pristine and oxidized antimonene layers, aiming to understand the
interplay between these materials and their collective impact on the bilayer
properties. Our results provide insight into how the properties of
antimony-based bilayer structures can be modified by adjusting stoichiometry
and stacking configurations.
New techniques in core-electron spectroscopy are necessary to resolve the
structures of oxides of $f$-elements and other strongly correlated materials
that are present only as powders and not as single crystals. Thus, accurate
quantum chemical methods need to be developed to calculate core spectroscopic
properties in such materials. In this contribution, we present an important
development in this direction, extending our fully adaptive real-space
multiwavelet basis framework to tackle the 4-component Dirac-Coulomb-Breit
Hamiltonian. We show that Multiwavelets are able to reproduce one-dimensional
grid-based approaches. They are however a fully three-dimensional approach
which can later on be extended to molecules and materials. Our Multiwavelet
implementation attained precise results irrespective of the chosen nuclear
model, provided that the error threshold is tight enough and the chosen
polynomial basis is sufficiently large. Furthermore, our results confirmed that
in two-electron species, the magnetic and Gauge contributions from $s$-orbitals
are identical in magnitude and can account for the experimental evidence from
$K$ and $L$ edges.
We investigate the electronic structure and the optical absorption onset of
hexagonal boron nitride bilayers with twist angles in the vicinity of
30$^\circ$. Our study is carried out with a tight-binding model that we
developed on purpose and validated against DFT simulations. We demonstrate that
approaching 30$^\circ$ (quasicrystal limit), all bilayers sharing the same
moir\'e supercell develop identical band structures, irrespective of their
stacking sequence. This band structure features a bundle of flat bands laying
slightly above the bottom conduction state which is responsible for an intense
peak at the onset of independent-particle absorption spectra. These results
reveal the presence of strong, stable and stacking-independent optical
properties in boron nitride 30$^\circ$-twisted bilayers. By carefully analyzing
the electronic spatial distribution, we elucidate the origin of these states as
due to interlayer B-B coupling. We take advantage of the the physical
transparency of the tight-binding parameters to derive a simple triangular
model based on the B sublattice that accurately describes the emergence of the
bundle. Being our conclusions very general, we predict that a similar bundle
should emerge in other close-to-30$^\circ$ bilayers, like transition metal
dichalcogenides, shedding new light on the unique potential of 2D materials.
We investigate the electronic and magnetic properties of the newly
synthesized double perovskites Y$_{2}$NiIrO$_{6}$ and La$_{2}$NiIrO$_{6}$,
using density functional calculations, crystal field theory, superexchange
pictures, and Monte Carlo simulations. We find that both systems are
antiferromagnetic (AFM) Mott insulators, with the high-spin Ni$^{2+}$
$t_{2g}$$^{6}e_{g}$$^{2}$ ($S=1$) and the low-spin Ir$^{4+}$ $t_{2g}$$^{5}$
($S=1/2$) configurations. We address that their lattice distortion induces
$t_{2g}$-$e_{g}$ orbital mixing and thus enables the normal Ni$^{+}$-Ir$^{5+}$
charge excitation with the electron hopping from the Ir `$t_{2g}$' to Ni
`$e_g$' orbitals, which promotes the AFM Ni$^{2+}$-Ir$^{4+}$ coupling.
Therefore, the increasing $t_{2g}$-$e_{g}$ mixing accounts for the enhanced
$T_{\rm N}$ from the less distorted La$_{2}$NiIrO$_{6}$ to the more distorted
Y$_{2}$NiIrO$_{6}$. Moreover, our test calculations find that in the otherwise
ideally cubic Y$_{2}$NiIrO$_{6}$, the Ni$^{+}$-Ir$^{5+}$ charge excitation is
forbidden, and only the abnormal Ni$^{3+}$-Ir$^{3+}$ excitation gives a weakly
ferromagnetic (FM) behavior. Furthermore, we find that owing to the crystal
field splitting, Hund exchange, and broad band formation in the highly
coordinated fcc sublattice, Ir$^{4+}$ ions are not in the $j_{\rm eff}=1/2$
state but in the $S=1/2$ state carrying a finite orbital moment by spin-orbit
coupling (SOC). This work clarifies the varying magnetism in Y$_{2}$NiIrO$_{6}$
and La$_{2}$NiIrO$_{6}$ associated with the lattice distortions.

Date of feed: Mon, 20 Nov 2023 01:30:00 GMT**Search terms: **(topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)|(flatband)|(flat.{1}band)|(LK.{1}99) **Quantum Hall Effect on Dirac electrons in modulated graphene. (arXiv:2311.10106v1 [cond-mat.mes-hall])**

M Arsalan Ali

**Itinerant Magnetism in the Triangular Lattice Hubbard Model at Half-doping: Application to Twisted Transition-Metal Dichalcogenides. (arXiv:2311.10146v1 [cond-mat.str-el])**

Yuchi He, Roman Rausch, Matthias Peschke, Christoph Karrasch, Philippe Corboz, Nick Bultinck, S.A. Parameswaran

**Time- and spectrum-resolved quantum-path interferometry reveals exciton dephasing in MoS$_2$ under strong-field conditions. (arXiv:2311.10286v1 [physics.optics])**

Yaxin Liu, Bingbing Zhu, Shicheng Jiang, Shenyang Huang, Mingyan Luo, Sheng Zhang, Hugen Yan, Yuanbo Zhang, Ruifeng Lu, Zhensheng Tao

**Tunable Inter-Moir\'e Physics in Consecutively-Twisted Trilayer Graphene. (arXiv:2311.10313v1 [cond-mat.mes-hall])**

Wei Ren, Konstantin Davydov, Ziyan Zhu, Jaden Ma, Kenji Watanabe, Takashi Taniguchi, Efthimios Kaxiras, Mitchell Luskin, Ke Wang

**Design and performance of an ultrahigh vacuum spectroscopic-imaging scanning tunneling microscope with a hybrid vibration isolation system. (arXiv:2311.10451v1 [cond-mat.mtrl-sci])**

Pei-Fang Chung, Balaji Venkatesan, Chih-Chuan Su, Jen-Te Chang, Hsu-Kai Cheng, Che-An Liu, Shan-An Yu, Syu-You Guan, Tien-Ming Chuang

**Enhancement of spin to charge conversion efficiency at the topological surface state by inserting normal metal spacer layer in the topological insulator based heterostructure. (arXiv:2311.10460v1 [cond-mat.mes-hall])**

Sayani Pal, Anuvab Nandi, Shambhu G. Nath, Pratap Kumar Pal, Kanav Sharma, Subhadip Manna, Anjan Barman, Chiranjib Mitra

**Testing the Renormalization of the von Klitzing Constant by Cavity Vacuum Fields. (arXiv:2311.10462v1 [cond-mat.mes-hall])**

Josefine Enkner, Lorenzo Graziotto, Felice Appugliese, Vasil Rokaj, Jie Wang, Michael Ruggenthaler, Christian Reichl, Werner Wegscheider, Angel Rubio, Jérôme Faist

**Interplay of phase segregation and chemical reaction: Crossover and effect on growth laws. (arXiv:2311.10464v1 [cond-mat.stat-mech])**

Shubham Thwal, Suman Majumder

**Graphene-based thermopneumatic generator for on-board pressure supply of soft robots. (arXiv:2311.10488v1 [cond-mat.mtrl-sci])**

Armin Reimers, Jannik Rank, Erik Greve, Morten Möller, Sören Kaps, Jörg Bahr, Rainer Adelung, Fabian Schütt

**Phase Coexistence of Mn Trimer Clusters and Antiferromagnetic Mn Islands on Ir(111). (arXiv:2311.10506v1 [cond-mat.mtrl-sci])**

Arturo Rodríguez-Sota, Vishesh Saxena, Jonas Spethmann, Roland Wiesendanger, Roberto Lo Conte, André Kubetzka, Kirsten von Bergmann

**Machine Learning Assisted Characterization of Labyrinthine Pattern Transitions. (arXiv:2311.10558v1 [cond-mat.soft])**

Kotaro Shimizu, Vinicius Yu Okubo, Rose Knight, Ziyuan Wang, Joseph Burton, Hae Yong Kim, Gia-Wei Chern, B. S. Shivaram

**Fluctuation-induced currents in suspended graphene nanoribbons: Adiabatic quantum pumping approach. (arXiv:2311.10560v1 [cond-mat.mes-hall])**

Federico D. Ribetto, Silvina A. Elaskar, Hernán L. Calvo, Raúl A. Bustos-Marún

**Revealing the Charge Density Wave Proximity Effect in Graphene on 1T-TaS$_2$. (arXiv:2311.10606v1 [cond-mat.mes-hall])**

Nikhil Tilak, Michael Altvater, Sheng-Hsiung Hung, Choong-Jae Won, Guohong Li, Taha Kaleem, Sang-Wook Cheong, Chung-Hou Chung, Horng-Tay Jeng, Eva Y. Andrei

**Discrete step walks reveal unconventional anomalous topology in synthetic photonic lattices. (arXiv:2311.10619v1 [cond-mat.mes-hall])**

Rabih El Sokhen, Álvaro Gómez-León, Albert F. Adiyatullin, Stéphane Randoux, Pierre Delplace, Alberto Amo

**Magnon topological transition in skyrmion crystal. (arXiv:2311.10622v1 [cond-mat.mes-hall])**

V. E. Timofeev, Yu. V. Baramygina, D. N. Aristov

**Critical ultrasonic propagation in magnetic fields. (arXiv:2311.10654v1 [cond-mat.stat-mech])**

A. Pawlak

**Phononic dynamical axion in magnetic Dirac insulators. (arXiv:2311.10674v1 [cond-mat.mes-hall])**

M. Nabil Y. Lhachemi, Ion Garate

**TODD-Graphene: A Novel Porous 2D Carbon Allotrope for High-Performance Lithium-Ion Batteries. (arXiv:2311.10704v1 [cond-mat.mtrl-sci])**

E. J. A. Santos, K. A. L. Lima, L. A. Ribeiro Junior

**A topological mechanism for robust and efficient global oscillations in biological networks. (arXiv:2302.11503v3 [physics.bio-ph] UPDATED)**

Chongbin Zheng, Evelyn Tang

**Transport and localization properties of excitations in one-dimensional lattices with diagonal disordered mosaic modulations. (arXiv:2303.13736v2 [cond-mat.dis-nn] UPDATED)**

Ba Phi Nguyen, Kihong Kim

**3D Ising CFT and Exact Diagonalization on Icosahedron: The Power of Conformal Perturbation Theory. (arXiv:2307.02540v3 [hep-th] UPDATED)**

Bing-Xin Lao, Slava Rychkov

**Unifying temperature definition in atomistic and field representations of conservation laws. (arXiv:2308.10127v2 [cond-mat.stat-mech] UPDATED)**

Youping Chen

**Graph topological transformations in space-filling cell aggregates. (arXiv:2309.04818v2 [cond-mat.soft] UPDATED)**

Tanmoy Sarkar, Matej Krajnc

**Krylov Complexity of Fermionic and Bosonic Gaussian States. (arXiv:2309.10382v2 [quant-ph] UPDATED)**

Kiran Adhikari, Adwait Rijal, Ashok Kumar Aryal, Mausam Ghimire, Rajeev Singh, Christian Deppe

**Electronic Properties and Interlayer Interactions in Antimony Oxide Homo- and Heterobilayers. (arXiv:2309.10653v2 [cond-mat.mtrl-sci] UPDATED)**

Stefan Wolff, Roland Gillen, Janina Maultzsch

**Full Breit Hamiltonian in the Multiwavelets Framework. (arXiv:2309.16183v2 [physics.chem-ph] UPDATED)**

Christian Tantardini, Roberto Di Remigio Eikås, Magnar Bjørgve, Stig Rune Jensen, Luca Frediani

**Emergence of flat bands in the quasicrystal limit of boron nitride twisted bilayers. (arXiv:2310.02937v2 [cond-mat.mtrl-sci] UPDATED)**

Lorenzo Sponza, Van Binh Vu, Elisa Serrano Richaud, Hakim Amara, Sylvain Latil

**Varying magnetism in the lattice distorted Y2NiIrO6 and La2NiIrO6. (arXiv:2310.18641v2 [cond-mat.mtrl-sci] UPDATED)**

Lu Liu, Ke Yang, Di Lu, Yaozhenghang Ma, Yuxuan Zhou, Hua Wu