Found 25 papers in cond-mat
Date of feed: Fri, 04 Aug 2023 00:30:00 GMT

Search terms: (topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)

Topological magnon-photon interaction for cavity magnonics. (arXiv:2308.01349v1 [cond-mat.mes-hall])
Jongjun M. Lee, Myung-Joong Hwang, Hyun-Woo Lee

The study of cavity magnonics and topological insulators has made significant advances over the past decade, however the possibility of combining the two fields is still unexplored. Here, we explore such connection by investigating hybrid cavity systems that incorporate both a ferromagnet and a topological insulator. We find that electrons in the topological surface state efficiently mediate the effective electric dipole coupling between the spin of the ferromagnet and the electric field of the cavity, in contrast with the conventional cavity magnonics theory based on magnetic dipole coupling. We refer to this coupling as topological magnon-photon interaction, estimating it one order of magnitude stronger than the conventional magnon-photon coupling, and showing that its sign can be manipulated. We discuss the potential of our proposed device to allow for scaling down and controlling the cavity system using electronics. Our results provide solid ground for exploring the functionalities enabled by merging cavity magnonics with topological insulators.

Absence of Weak Localization on Negative Curvature Surfaces. (arXiv:2308.01351v1 [cond-mat.dis-nn])
Jonathan B. Curtis, Prineha Narang, Victor Galitski

The interplay between disorder and quantum interference leads to a wide variety of physical phenomena including celebrated Anderson localization -- the complete absence of diffusive transport due to quantum interference between different particle trajectories. In two dimensions, any amount of disorder is thought to induce localization of all states at long enough length scales, though this may be prevented if bands are topological or have strong spin-orbit coupling. In this note, we present a simple argument providing another mechanism for disrupting localization: by tuning the underlying curvature of the manifold on which diffusion takes place. We show that negative curvature manifolds contain a natural infrared cut off for the probability of self returning paths. We provide explicit calculations of the Cooperon -- directly related to the weak-localization corrections to the conductivity -- in hyperbolic space. It is shown that constant negative curvature leads to a rapid growth in the number of available trajectories a particle can coherently traverse in a given time, reducing the importance of interference effects and restoring classical diffusive behavior even in the absence of inelastic collisions. We conclude by arguing that this result may be amenable to experimental verification through the use of quantum simulators.

Revival of antibiskyrmionic magnetic phases in bilayer NiI$_2$. (arXiv:2308.01484v1 [cond-mat.mes-hall])
Jyotirish Das, Muhammad Akram, Onur Erten

Magnetic skyrmions are topologically protected spin textures with potential applications in memory and logic devices. Skyrmions have been commonly observed in systems with Dzyaloshinskii-Moriya interaction due to broken inversion symmetry. Yet, recent studies suggest that skyrmions can also be stabilized in systems with inversion symmetry such as Ni-based dihalides due to magnetic frustration. In this article, we employ atomistic simulations to investigate chiral magnetic phases in bilayers of NiI$_2$ and NiBr$_2$. We show that the antiferromagnetic interlayer coupling introduces an additional magnetic frustration and gives rise to a variety of novel spin textures with different topological charges. Specifically for NiI$_2$, we observe that the skyrmions with the in-plane component of spins wrapping around twice (biskyrmions) have an enhanced stability compared to the monolayer case. We also study the polarization induced by the non-colinear magnetic order in NiI$_2$ bilayers and show that the polarization of the topologically nontrivial phases is negligible compared to the spiral phases. Thus, we conclude that polarization measurements can be an indirect route for detecting skyrmions in upcoming experiments.

Polarity of the fermionic condensation in the $p$-wave Kitaev model on a square lattice. (arXiv:2308.01494v1 [cond-mat.str-el])
E. S. Ma, Z. Song

In a $p$-wave Kitaev model, the nearest neighbor pairing term results in the formation of the Bardeen-Cooper-Schrieffer (BCS) pair in the ground state. In this work, we study the fermionic condensation of real-space pairs in a $% p $-wave Kitaev model on a square lattice with a uniform phase gradient pairing term along both directions. The exact solution shows that the ground state can be expressed in a coherent-state-like form, indicating the condensation of a collective pairing mode, which is the superposition of different configurations of pairs in real space. The amplitudes of each configuration depend not only on the size but also on the orientation of the pair. We employ three quantities to characterize the ground state in the thermodynamic limit. (i) A BCS-pair order parameter is introduced to characterize the phase diagram, consisting of gapful and topological gapless phases. (ii) The particle-particle correlation length is obtained to reveal the polarity of the pair condensation. In addition, (iii) a pair-pair correlator is analytically derived to indicate the possessing of off-diagonal long-range order. Our work proposes an alternative method for understanding fermionic condensation.

Successful growth and room temperature ambient-pressure magnetic levitation of LK-99. (arXiv:2308.01516v1 [cond-mat.supr-con])
Hao Wu, Li Yang, Bichen Xiao, Haixin Chang

Recently, Sukbae Lee et al. reported inspiring experimental findings on the atmospheric superconductivity of a modified lead apatite crystal (LK-99) at room temperature (10.6111/JKCGCT.2023.33.2.061, arXiv: 2307.12008, arXiv: 2307.12037). They claimed that the synthesized LK-99 materials exhibit the Meissner levitation phenomenon of superconductors and have a superconducting transition temperature (Tc) higher than 400 K. Here, for the first time, we successfully verify and synthesize the LK-99 crystals which can be magnetically levitated with larger levitated angle than Sukbae Lee's sample at room temperature. It is expected to realize the true potential of room temperature, non-contact superconducting magnetic levitation in near future.

High-throughput screening of Weyl semimetals. (arXiv:2308.01663v1 [cond-mat.mtrl-sci])
Davide Grassano, Davide Campi, Nicola Marzari

Topological Weyl semimetals represent a novel class of non-trivial materials, where band crossings with linear dispersions take place at generic momenta across reciprocal space. These crossings give rise to low-energy properties akin to those of Weyl fermions, and are responsible for several exotic phenomena. Up to this day, only a handful of Weyl semimetals have been discovered, and the search for new ones remains a very active area. The main challenge on the computational side arises from the fact that many of the tools used to identify the topological class of a material do not provide a complete picture in the case of Weyl semimetals. In this work, we propose an alternative and inexpensive, criterion to screen for possible Weyl fermions, based on the analysis of the band structure along high-symmetry directions in the absence of spin-orbit coupling. We test the method by running a high-throughput screening on a set of 5455 inorganic bulk materials and identify 49 possible candidates for topological properties. A further analysis, carried out by identifying and characterizing the crossings in the Brillouin zone, shows us that 3 of these candidates are Weyl semimetals. Interestingly, while these 3 materials underwent other high-throughput screenings, none had revealed their topological behavior before.

Disorder Effects on the Quasiparticle and Transport Properties of Two-Dimensional Dirac Fermionic Systems. (arXiv:2308.01680v1 [cond-mat.mes-hall])
Bo Fu, Yanru Chen, Weiwei Chen, Wei Zhu, Ping Cui, Qunxiang Li, Zhenyu Zhang, Qinwei Shi

Despite extensive existing studies, a complete understanding of the role of disorder in affecting the physical properties of two-dimensional Dirac fermionic systems remains a standing challenge, largely due to obstacles encountered in treating multiple scattering events for such inherently strong scattering systems. Using graphene as an example and a nonperturbative numerical technique, here we reveal that the low energy quasiparticle properties are considerably modified by multiple scattering processes even in the presence of weak scalar potentials. We extract unified power-law energy dependences of the self-energy with fractional exponents from the weak scattering limit to the strong scattering limit from our numerical analysis, leading to sharp reductions of the quasiparticle residues near the Dirac point, eventually vanishing at the Dirac point. The central findings stay valid when the Anderson-type impurities are replaced by correlated Gaussian- or Yukawa-type disorder with varying correlation lengths. The improved understanding gained here also enables us to provide better interpretations of the experimental observations surrounding the temperature and carrier density dependences of the conductivity in ultra-high mobility graphene samples. The approach demonstrated here is expected to find broad applicability in understanding the role of various other types of impurities in two-dimensional Dirac systems.

Flavor-wave theory with quasiparticle damping at finite temperatures: Application to chiral edge modes in the Kitaev model. (arXiv:2308.01711v1 [cond-mat.str-el])
Shinnosuke Koyama, Joji Nasu

We propose a theoretical framework to investigate elementary excitations at finite temperatures within a localized electron model that describes the interactions between multiple degrees of freedom, such as quantum spin models and Kugel-Khomskii models. Thus far, their excitation structures have been mainly examined using the linear flavor-wave theory, an SU($N$) generalization of the linear spin-wave theory. These techniques introduce noninteracting bosonic quasiparticles as elementary excitations from the ground state, thereby elucidating numerous physical phenomena, including excitation spectra and transport properties characterized by topologically nontrivial band structures. Nevertheless, the interactions between quasiparticles cannot be ignored in systems exemplified by $S=1/2$ quantum spin models, where strong quantum fluctuations are present. Recent studies have investigated the effects of quasiparticle damping at zero temperature in such models. In our study, extending this approach to the flavor-wave theory for general localized electron models, we construct a comprehensive method to calculate excitation spectra with the quasiparticle damping at finite temperatures. We apply our method to the Kitaev model under magnetic fields, a typical example of models with topologically nontrivial magnon bands. Our calculations reveal that chiral edge modes undergo significant damping in weak magnetic fields, amplifying the damping rate by the temperature increase. This effect is caused by collisions with thermally excited quasiparticles. Since our approach starts from a general Hamiltonian, it will be widely applicable to other localized systems, such as spin-orbital coupled systems derived from multi-orbital Hubbard models in the strong correlation limit.

Energy spectrum of valence band in HgTe quantum wells on the way from a two to the three dimensional topological insulator. (arXiv:2308.01745v1 [cond-mat.mes-hall])
G. M. Minkov, O. E. Rut, A. A. Sherstobitov, S. A. Dvoretski, N. N. Mikhailov, V. Ya. Aleshkin

The magnetic field, temperature dependence and the Hall effect have been measured in order to determine the energy spectrum of the valence band in HgTe quantum wells with the width (20-200)nm. The comparison of hole densities determined from the period Shubnikov-de Haas oscillations and the Hall effect shows that states at the top of valence band are double degenerate in teh entry quantum wells width the width range. The cyclotron mass determined from temperature dependence of SdH oscillations increases monotonically from (0.2-0.3) mass of the free electron, with increasing hole density from 2e11 to 6e11 cm^-2. The determined dependence has been compared to theoretical one calculate within the four band kp model. The experimental dependence was found to be strongly inconsistent with this predictions. It has been shown that the inclusion of additional factors (electric field, strain) does not remove the contradiction between experiment and theory. Consequently it is doubtful that the mentioned kp calculations adequately describe the valence band for any width of quantum well.

Anyons in a highly-entangled toric xy model. (arXiv:2308.01765v1 [cond-mat.str-el])
Milo Moses, Konrad Deka

While ostensibly coined in 1989 by Xiao-Gang Wen, the term "topological order" has been in use since 1972 by Kosterlitz-Thouless to describe the behavior of the classical xy model. It has been noted that the xy model does not have Wen's topological order since it is also subject a non-topological U(1) gauge action. We show in a sense this is the only obstruction. That is, if the xy model evolves quantumly into gauge invariant states then one recovers pure topological order. In fact, we show the quantum xy topological order is an infinite lattice limit of Kitaev's quantum double model applied to the group G=Z.

Coupled quantum vortex kinematics and Berry curvature in real space. (arXiv:2202.13210v3 [physics.optics] UPDATED)
Lorenzo Dominici, Amir Rahmani, David Colas, Dario Ballarini, Milena De Giorgi, Giuseppe Gigli, Fabrice P. Laussy, Daniele Sanvitto, Nina Voronova

The Berry curvature provides a powerful tool to unify several branches of science through their geometrical aspect: topology, energy bands, spin and vector fields. While quantum defects -- phase vortices and skyrmions -- have been in the spotlight, as rotational entities in condensates, superfluids and optics, their dynamics in multi-component fields remain little explored. Here we use two-component microcavity polaritons to imprint a dynamical pseudospin texture in the form of a double full Bloch beam, a conformal continuous vortex beyond unitary skyrmions. The Berry curvature plays a key role to link various quantum spaces available to describe such textures. It explains for instance the ultrafast spiraling in real space of two singular vortex cores, providing in particular a simple expression -- also involving the complex Rabi frequency -- for their intricate velocity. Such Berry connections open new perspectives for understanding and controlling highly-structured quantum objects, including strongly asymmetric cases or even higher multi-component fields.

Hund bands in spectra of multiorbital systems. (arXiv:2210.11209v3 [cond-mat.str-el] UPDATED)
M. Środa, J. Mravlje, G. Alvarez, E. Dagotto, J. Herbrych

Spectroscopy experiments are routinely used to characterize the behavior of strongly correlated systems. An in-depth understanding of the different spectral features is thus essential. Here, we show that the spectrum of the multiorbital Hubbard model exhibits unique Hund \ms{bands} that occur at energies given only by the Hund coupling $J_\mathrm{H}$, as distinct from the Hubbard satellites following the interaction $U$. We focus on experimentally relevant single-particle and optical spectra that we calculate for a model related to iron chalcogenide ladders. The calculations are performed via the density-matrix renormalization group and Lanczos methods. The generality of the implications is verified by considering a generic multiorbital model within dynamical mean-field theory.

Baby Skyrmion in two-component holographic superfluids. (arXiv:2210.12490v3 [hep-th] UPDATED)
Shunhui Yao, Yu Tian, Peng Yang, Hongbao Zhang

In the two-component Ginzburg-Landau theory of superfluidity, a pair of fractional vortices form a composite type of topological defect, usually referred to as a baby skyrmion. In this paper, we initiate the construction of such a baby skyrmion in the holographic model of two-component superfluids. As a result, two types of baby skyrmion configurations are found, where the monopole-type of one is constructed directly by solving the static equations of motion while the dipole-type of one is obtained by resorting to the time evolution method. In addition, we find that the existence of these two types of baby skyrmion depends on the inter-component coupling, reminiscent of the situation in the baby skyrmion model.

Variational Tensor Wavefunctions for the Interacting Quantum Spin Hall Phase. (arXiv:2302.03879v2 [cond-mat.str-el] UPDATED)
Yixin Ma, Shenghan Jiang, Chao Xu

The quantum spin hall (QSH) phase, also known as the 2D topological insulator, is characterized by protected helical edge modes arising from time reversal symmetry. While initially proposed for band insulators, this phase can also manifest in strongly-correlated systems where conventional band theory fails. To overcome the challenge of simulating this phase in realistic correlated models, we propose a novel framework utilizing fermionic tensor network states. Our approach involves constructing a tensor representation of the fixed-point wavefunction based on an exact solvable model, enabling us to derive a set of tensor equations governing the transformation rules of local tensors under symmetry operations. These tensor equations lead to the anomalous edge theory, which provides a comprehensive description of the QSH phase. By solving these tensor equations, we obtain variational ansatz for the QSH phase, which we subsequently verify through numerical calculations. This method serves as an initial step towards employing tensor algorithms to simulate the QSH phase in strongly-correlated systems, opening new avenues for investigating and understanding topological phenomena in complex materials.

BCS-BCS crossover between atomic and molecular superfluids in a Bose-Fermi mixture. (arXiv:2302.04617v2 [cond-mat.quant-gas] UPDATED)
Yixin Guo, Hiroyuki Tajima, Tetsuo Hatsuda, Haozhao Liang

We theoretically examine a continuity between atomic and molecular Fermi superfluids in a Bose-Fermi mixture near the Feshbach resonance. Considering a two-channel model describing the Feshbach resonance between Fermi and Bose atoms, we have constructed the mean-field framework based on the perturbative expansion of the Feshbach atom-dimer coupling. The resulting effective Hamiltonian exhibits not only the continuity between atom-atom to molecule-molecule Cooper pairings but also becomes equivalent to the two-band-superconductor model with Suhl-Matthias-Walker type pair-exchange coupling. We demonstrate how these atomic and molecular Fermi superfluids coexist within the two-band-like superfluid theory. The pair-exchange coupling and resulting superfluid gaps are found to be strongly enhanced near the Feshbach resonance due to the interplay between the infrared singularity of Bogoliubov phonons and their Landau damping arising from the coupling with fermions. The pair-exchange coupling can be probed via the observation of the intrinsic Josephson effect between atomic and molecular superfluids.

Compact expansion of a repulsive suspension. (arXiv:2302.14756v2 [cond-mat.soft] UPDATED)
Matan Yah Ben Zion, Naomi Oppenheimer

Short-range repulsion governs the dynamic behavior of matter across length scales, from atoms to animals. As the density increases, the dynamics transition from nearest-neighbor to many-body interactions, posing a challenge for an analytical description. Here we use theory, simulations, and experiments to show that a suspension of particles with short-range repulsion spreads compactly. Unlike the diffusive boundary of a spreading drop of Brownian particles, a compact expansion is characterized by a density profile that is strictly zero beyond a cutoff distance. Starting from the microscopic interactions, we derive an effective, non-linear diffusion equation and find that the dynamics exhibit two distinct transitions: (1) when very dense, particle-particle interactions extend beyond nearest neighbors, and the ensemble grows in a self-similar fashion as time to the power of 1/4. (2) at lower densities, nearest-neighbor interactions dominate, and the expansion slows to logarithmic growth. We examine the second regime experimentally by monitoring the expansion of a dense suspension of charge-stabilized colloids. Using simulations of thousands of particles, we observe the continuous crossover between the self-similar and the logarithmic dynamics. Our results are general and robust, with practical implications in engineering and pharmaceutical industries, where suspensions must operate at extreme densities.

Measurement Quantum Cellular Automata and Anomalies in Floquet Codes. (arXiv:2304.01277v2 [quant-ph] UPDATED)
David Aasen, Jeongwan Haah, Zhi Li, Roger S. K. Mong

We investigate the evolution of quantum information under Pauli measurement circuits. We focus on the case of one- and two-dimensional systems, which are relevant to the recently introduced Floquet topological codes. We define local reversibility in context of measurement circuits, which allows us to treat finite depth measurement circuits on a similar footing to finite depth unitary circuits. In contrast to the unitary case, a finite depth locally reversible measurement circuit can implement a translation in one dimension. A locally reversible measurement circuit in two dimensions may also induce a flow of logical information along the boundary. We introduce "measurement quantum cellular automata" which unifies these ideas and define an index in one dimension to characterize the flow of logical operators. We find a $\mathbb{Z}_2$ bulk invariant for two-dimensional Floquet topological codes which indicates an obstruction to having a trivial boundary. We prove that the Hastings-Haah honeycomb code belongs to a class with such obstruction, which means that any boundary must have either nonlocal dynamics, period doubled, or admits anomalous boundary flow of quantum information.

Magnon-magnon interaction in monolayer MnBi$_2$Te$_4$. (arXiv:2304.09637v2 [cond-mat.str-el] UPDATED)
Yiqun Liu, Liangjun Zhai, Songsong Yan, Di Wang, Xiangang Wan

MnBi$_2$Te$_4$, the first confirmed intrinsic antiferromagnetic topological insulator, has garnered increasing attention in recent years. Here we investigate the energy correction and lifetime of magnons in MnBi$_2$Te$_4$ caused by magnon-magnon interaction. Firstly, a calculation based on the density functional theory (DFT) was performed to get the parameters of the magnetic Hamiltonian of MnBi$_2$Te$_4$. Subsequently, the perturbation method of many-body Green's function was employed and the 1st-order self-energy [$\Sigma^{(1)}(\bm k)$] and 2nd-order self-energy [$\Sigma^{(2)}(\bm k,\varepsilon_{\bm k})$] of magnon were obtained. Numerical computations reveal that the corrections from both $\Sigma^{(1)}(\bm k)$ and $\Sigma^{(2)}(\bm k,\varepsilon_{\bm k})$ strongly rely on momentum and temperature, with the energy renormalization near the Brillouin zone (BZ) boundary being significantly more pronounced than that near the BZ center. Furthermore, our findings indicate the occurrence of dip structures in the renormalized magnon spectrum near the $\rm K$ and $\rm M$ points. These dip structures are determined to be attributed to the influence of $\Sigma^{(2)}(\bm k,\varepsilon_{\bm k})$.

Non-linear and negative effective diffusivity of optical excitations in moir\'e-free heterobilayers. (arXiv:2306.12339v2 [cond-mat.mes-hall] UPDATED)
Edith Wietek, Matthias Florian, Jonas M. Göser, Takashi Taniguchi, Kenji Watanabe, Alexander Högele, Mikhail M. Glazov, Alexander Steinhoff, Alexey Chernikov

Interlayer exciton diffusion is studied in atomically-reconstructed MoSe2/WSe2 heterobilayers with suppressed disorder. Local atomic registry is confirmed by characteristic optical absorption, circularly-polarized photoluminescence, and g-factor measurements. Using transient microscopy we observe propagation properties of interlayer excitons that are independent from trapping at moir\'e- or disorder-induced local potentials. Confirmed by characteristic temperature dependence for free particles, linear diffusion coefficients of interlayer excitons at liquid helium temperature and low excitation densities are almost 1000 times higher than in previous observations. We further show that exciton-exciton repulsion and annihilation contribute nearly equally to non-linear propagation by disentangling the two processes in the experiment and simulations. Finally, we demonstrate effective shrinking of the light-emission over time across several 100's of picoseconds at the transition from exciton- to the plasma-dominated regimes. Supported by microscopic calculations for bandgap renormalization to identify Mott threshold, this indicates transient crossing between rapidly expanding, short-lived electron-hole plasma and slower, long-lived exciton populations.

Path integral simulation of exchange interactions in CMOS spin qubits. (arXiv:2307.03455v3 [cond-mat.mes-hall] UPDATED)
Jesús D. Cifuentes, Philip Y. Mai, Frédéric Schlattner, H. Ekmel Ercan, MengKe Feng, Christopher C. Escott, Andrew S. Dzurak, Andre Saraiva

The boom of semiconductor quantum computing platforms created a demand for computer-aided design and fabrication of quantum devices. Path integral Monte Carlo (PIMC) can have an important role in this effort because it intrinsically integrates strong quantum correlations that often appear in these multi-electron systems. In this paper we present a PIMC algorithm that estimates exchange interactions of three-dimensional electrically defined quantum dots. We apply this model to silicon metal-oxide-semiconductor (MOS) devices and we benchmark our method against well-tested full configuration interaction (FCI) simulations. As an application, we study the impact of a single charge trap on two exchanging dots, opening the possibility of using this code to test the tolerance to disorder of CMOS devices. This algorithm provides an accurate description of this system, setting up an initial step to integrate PIMC algorithms into development of semiconductor quantum computers.

Dissipative phase transitions and passive error correction. (arXiv:2307.09512v2 [quant-ph] UPDATED)
Yu-Jie Liu, Simon Lieu

We classify different ways to passively protect classical and quantum information, i.e. we do not allow for syndrome measurements, in the context of local Lindblad models for spin systems. Within this family of models, we suggest that passive error correction is associated with nontrivial phases of matter and propose a definition for dissipative phases based on robust steady state degeneracy of a Lindbladian in the thermodynamic limit. We study three thermalizing models in this context: the 2D Ising model, the 2D toric code, and the 4D toric code. In the low-temperature phase, the 2D Ising model hosts a robust classical steady state degeneracy while the 4D toric code hosts a robust quantum steady state degeneracy. We perturb the models with terms that violate detailed balance and observe that qualitative features remain unchanged, suggesting that $\mathbb{Z}_2$ symmetry breaking in a Lindbladian is useful to protect a classical bit while intrinsic topological order protects a qubit.

Enumeration and representation of spin space groups. (arXiv:2307.10369v2 [cond-mat.mtrl-sci] UPDATED)
Jun Ren, Xiaobing Chen, Yanzhou Zhu, Yutong Yu, Ao Zhang, Jiayu Li, Yuntian Liu, Caiheng Li, Qihang Liu

Those fundamental properties, such as phase transitions, Weyl fermions and spin excitation, in all magnetic ordered materials was ultimately believed to rely on the symmetry theory of magnetic space groups. Recently, it has come to light that a more comprehensive group, known as the spin space group (SSG), which combines separate spin and spatial operations, is necessary to fully characterize the geometry and physical properties of magnetic ordered materials such as altermagnets. However, the basic theory of SSG has been seldomly developed. In this work, we present a systematic study of the enumeration and the representation theory of SSG. Starting from the 230 crystallographic space groups and finite translational groups with a maximum order of 8, we establish an extensive collection of over 80,000 SSGs under a four-segment nomenclature. We then identify inequivalent SSGs specifically applicable to collinear, coplanar, and noncoplanar magnetic configurations. Moreover, we derive the irreducible co-representations of the little group in momentum space within the SSG framework. Finally, we illustrate the SSGs and band degeneracies resulting from SSG symmetries through several representative material examples, including a well-known altermagnet RuO2, and a spiral magnet CeAuAl3. Our work advances the field of group theory in describing magnetic ordered materials, opening up avenues for deeper comprehension and further exploration of emergent phenomena in magnetic materials.

Views on gravity from condensed matter physics. (arXiv:2307.14370v3 [cond-mat.other] UPDATED)
G.E. Volovik

In the paper "Life, the Universe, and everything--42 fundamental questions", Roland Allen and Suzy Lidstr\"om presented personal selection of the fundamental questions. Here, based on the condensed matter experience, we suggest the answers to some questions concerning the vacuum energy, black hole entropy and the origin of gravity. In condensed matter we know both the many-body phenomena emerging on the macroscopic level and the microscopic (atomic) physics, which generates this emergence. It appears that the same macroscopic phenomenon may be generated by essentially different microscopic backgrounds. This points to various possible directions in study of the deep quantum vacuum of our Universe.

Helical Separation Effect and helical heat transport for Dirac fermions. (arXiv:2307.14987v2 [hep-th] UPDATED)
Victor E. Ambruş, Maxim N. Chernodub

An ensemble of massless fermions can be characterized by its total helicity charge given by the sum of axial charges of particles minus the sum of axial charges of antiparticles. We show that charged massless fermions develop a dissipationless flow of helicity along the background magnetic field. We dub this transport phenomenon as the Helical Separation Effect (HSE). Contrary to its chiral cousin, the Chiral Separation Effect, the HSE produces the helical current in a neutral plasma in which all chemical potentials vanish. In addition, we uncover the Helical Magnetic Heat Effect which generates a heat flux of Dirac fermions along the magnetic field in the presence of non-vanishing helical charge density. We also discuss possible hydrodynamic modes associated with the HSE in neutral plasma.

A Platform for Far-Infrared Spectroscopy of Quantum Materials at Millikelvin Temperatures. (arXiv:2308.00610v2 [cond-mat.mes-hall] UPDATED)
Michael Onyszczak, Ayelet J. Uzan, Yue Tang, Pengjie Wang, Yanyu Jia, Guo Yu, Tiancheng Song, Ratnadwip Singha, Jason F. Khoury, Leslie M. Schoop, Sanfeng Wu

Optical spectroscopy of quantum materials at ultralow temperatures is rarely explored, yet it may provide critical characterizations of quantum phases not possible using other approaches. We describe the development of a novel experimental platform that enables optical spectroscopic studies, together with standard electronic transport, of materials at millikelvin temperatures inside a dilution refrigerator. The instrument is capable of measuring both bulk crystals and micron-sized two-dimensional van der Waals materials and devices. We demonstrate the performance by implementing photocurrent-based Fourier transform infrared spectroscopy on a monolayer WTe$_2$ device and a multilayer 1T-TaS$_2$ crystal, with a spectral range available from near-infrared to terahertz range and in magnetic fields up to 5 T. In the far-infrared regime, we achieve spectroscopic measurements at a base temperature as low as ~ 43 mK and a sample electron temperature of ~ 450 mK. Possible experiments and potential future upgrades of this versatile instrumental platform are envisioned.

Found 10 papers in prb
Date of feed: Fri, 04 Aug 2023 03:17:06 GMT

Search terms: (topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)

Optical coherence properties of Kramers' rare-earth ions at the nanoscale for quantum applications
Mohammed K. Alqedra, Chetan Deshmukh, Shuping Liu, Diana Serrano, Sebastian P. Horvath, Safi Rafie-Zinedine, Abdullah Abdelatief, Lars Rippe, Stefan Kröll, Bernardo Casabone, Alban Ferrier, Alexandre Tallaire, Philippe Goldner, Hugues de Riedmatten, and Andreas Walther
Author(s): Mohammed K. Alqedra, Chetan Deshmukh, Shuping Liu, Diana Serrano, Sebastian P. Horvath, Safi Rafie-Zinedine, Abdullah Abdelatief, Lars Rippe, Stefan Kröll, Bernardo Casabone, Alban Ferrier, Alexandre Tallaire, Philippe Goldner, Hugues de Riedmatten, and Andreas Walther

Rare Earth (RE) ion doped nanomaterials are promising candidates for a range of quantum technology applications. Among RE ions, the so-called Kramers' ions possess spin transitions in the GHz range at low magnetic fields, which allows for high-bandwidth multimode quantum storage, fast qubit operatio…

[Phys. Rev. B 108, 075107] Published Thu Aug 03, 2023

Non-Hermitian boost deformation
Taozhi Guo, Kohei Kawabata, Ryota Nakai, and Shinsei Ryu
Author(s): Taozhi Guo, Kohei Kawabata, Ryota Nakai, and Shinsei Ryu

The Hatano-Nelson model is one of the most prototypical non-Hermitian models that exhibit the intrinsic non-Hermitian topological phases and the concomitant skin effect. These phenomena unique to non-Hermitian topological systems originate from the Galilean transformation. Here, we extend such an id…

[Phys. Rev. B 108, 075108] Published Thu Aug 03, 2023

Engineering topologically protected zero-dimensional interface end states in antiferromagnetic heterojunction graphene nanoflakes
Cheng-Ming Miao, Yu-Hao Wan, Qing-Feng Sun, and Ying-Tao Zhang
Author(s): Cheng-Ming Miao, Yu-Hao Wan, Qing-Feng Sun, and Ying-Tao Zhang

We investigate the energy band structure and energy levels of a heterojunction composed of two antiferromagnetic graphene nanoflakes with opposite in-plane antiferromagnetic orderings, in which the modified Kane-Mele model is employed. Before forming an antiferromagnetic graphene heterojunction, the…

[Phys. Rev. B 108, 075401] Published Thu Aug 03, 2023

Emerging exceptional point with breakdown of the skin effect in non-Hermitian systems
Sayan Jana and Lea Sirota
Author(s): Sayan Jana and Lea Sirota

We study the interplay of two distinct non-Hermitian parameters: directional coupling and on-site gain and loss, together with topology, in coupled one-dimensional non-Hermitian Su-Schrieffer-Heeger (SSH) chains. The SSH model represents one of the simplest two-band models that features boundary-loc…

[Phys. Rev. B 108, 085104] Published Thu Aug 03, 2023

Observation of field-induced single-ion magnetic anisotropy in a multiorbital Kondo alloy ${(\mathrm{Lu},\mathrm{Yb})\mathrm{Rh}}_{2}{\mathrm{Zn}}_{20}$
T. Kitazawa, Y. Ikeda, T. Sakakibara, A. Matsuo, Y. Shimizu, Y. Tokunaga, Y. Haga, K. Kindo, Y. Nambu, K. Ikeuchi, K. Kamazawa, M. Ohkawara, and M. Fujita
Author(s): T. Kitazawa, Y. Ikeda, T. Sakakibara, A. Matsuo, Y. Shimizu, Y. Tokunaga, Y. Haga, K. Kindo, Y. Nambu, K. Ikeuchi, K. Kamazawa, M. Ohkawara, and M. Fujita

We demonstrate field-induced single-ion magnetic anisotropy resulting from the multiorbital Kondo effect on the diluted ytterbium alloy $({\mathrm{Lu}}_{1−x}{\mathrm{Yb}}_{x}){\mathrm{Rh}}_{2}{\mathrm{Zn}}_{20}$. Single-ion anisotropic metamagnetic behavior is revealed in low-temperature regions whe…

[Phys. Rev. B 108, 085105] Published Thu Aug 03, 2023

Quantum oscillations in a doped Mott insulator beyond Onsager's relation
Valentin Leeb and Johannes Knolle
Author(s): Valentin Leeb and Johannes Knolle

The Fermi surface — the manifold of gapless excitations forming due to Pauli’s famous exclusion principle— determines all electronic properties of metals. In 1952 Lars Onsager discovered how to measure a Fermi surface by studying the response of a metallic material as a function of an applied magnetic field. In fact, observables like electrical resistivity or the magnetization oscillate as a function of inverse field. Onsager’s relation forms the basis for our understanding of electronic properties of metals and is used in many experimental labs around the world. Here, the authors find that, in the presence of strong interactions between electrons, Onsager’s relation can be violated and they provide the first rigorous calculations of this effect. In general, solving for the emergent Landau levels of a strongly interacting material in a magnetic field is a hard problem. The methodological progress made here is enabled by concentrating on an exactly soluble model with infinite-range interactions. This research establishes the importance of inter Landau level interactions for understanding correlated materials in magnetic fields.

[Phys. Rev. B 108, 085106] Published Thu Aug 03, 2023

First-order phase transitions within Weyl type of materials at low temperatures
Y. M. P. Gomes, Everlyn Martins, Marcus Benghi Pinto, and Rudnei O. Ramos
Author(s): Y. M. P. Gomes, Everlyn Martins, Marcus Benghi Pinto, and Rudnei O. Ramos

We analyze the possible dynamical chiral symmetry-breaking patterns taking place within Weyl type of materials. Here, these systems are modeled by the $(2+1)$-dimensional Gross-Neveu model with a tilt in the Dirac cone. The optimized perturbation theory (OPT) is employed in order to evaluate the eff…

[Phys. Rev. B 108, 085107] Published Thu Aug 03, 2023

Plasma echoes in graphene
Marinko Jablan
Author(s): Marinko Jablan

Plasma echo is a dramatic manifestation of plasma damping process reversibility. In this paper we calculate temporal and spatial plasma echoes in graphene in the acoustic plasmon regime when echoes dominate over plasmon emission. We show an extremely strong spatial echo response and discuss how elec…

[Phys. Rev. B 108, 085404] Published Thu Aug 03, 2023

Apparent Kondo effect in Moiré transition metal dichalcogenide bilayers: Heavy fermions versus disorder
Prathyush P. Poduval, Katharina Laubscher, and Sankar Das Sarma
Author(s): Prathyush P. Poduval, Katharina Laubscher, and Sankar Das Sarma

A recent work by Zhao et al. [Nature (London) 616, 61 (2023)] reported the realization of a synthetic Kondo lattice in a gate-tunable Moiré transition metal dichalcogenide bilayer system. The observation of a Kondo lattice is supported by a plateau (or dip, depending on filling) in the temperature d…

[Phys. Rev. B 108, 085405] Published Thu Aug 03, 2023

Chemical potential and magnetic field effects on graphene magnetoplasmons
Ningning Wang, Linhui Ding, and Weihua Wang
Author(s): Ningning Wang, Linhui Ding, and Weihua Wang

Due to its strong magneto-optical response, plasmons in graphene can be actively tuned by a static magnetic field, resulting in another quasiparticle called graphene magnetoplasmon (GMP). In this work, we theoretically investigate GMPs in graphene disks with their two halves subject to two magnetic …

[Phys. Rev. B 108, 085406] Published Thu Aug 03, 2023

Found 3 papers in prl
Date of feed: Fri, 04 Aug 2023 03:17:07 GMT

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Manipulating Growth and Propagation of Correlations in Dipolar Multilayers: From Pair Production to Bosonic Kitaev Models
Thomas Bilitewski and Ana Maria Rey
Author(s): Thomas Bilitewski and Ana Maria Rey

We study the nonequilibrium dynamics of dipoles confined in multiple stacked two-dimensional layers realizing a long-range interacting quantum spin $1/2$ XXX model. We demonstrate that strong in-plane interactions can protect a manifold of collective layer dynamics. This then allows us to map the ma…

[Phys. Rev. Lett. 131, 053001] Published Thu Aug 03, 2023

Fermi Arc Reconstruction in Synthetic Photonic Lattice
D.-H.-Minh Nguyen, Chiara Devescovi, Dung Xuan Nguyen, Hai Son Nguyen, and Dario Bercioux
Author(s): D.-H.-Minh Nguyen, Chiara Devescovi, Dung Xuan Nguyen, Hai Son Nguyen, and Dario Bercioux

The chiral surface states of Weyl semimetals have an open Fermi surface called a Fermi arc. At the interface between two Weyl semimetals, these Fermi arcs are predicted to hybridize and alter their connectivity. In this Letter, we numerically study a one-dimensional (1D) dielectric trilayer grating …

[Phys. Rev. Lett. 131, 053602] Published Thu Aug 03, 2023

Anomalous Reentrant $5/2$ Quantum Hall Phase at Moderate Landau-Level-Mixing Strength
Sudipto Das, Sahana Das, and Sudhansu S. Mandal
Author(s): Sudipto Das, Sahana Das, and Sudhansu S. Mandal

A successful probing of the neutral Majorana mode in recent thermal Hall conductivity measurements opines in favor of the particle-hole symmetric Pfaffian (PH-Pf) topological order, contrasting the theoretical predictions of Pfaffian or anti-Pfaffian phases. Here we report a reentrant anomalous quan…

[Phys. Rev. Lett. 131, 056202] Published Thu Aug 03, 2023

Found 2 papers in pr_res
Date of feed: Fri, 04 Aug 2023 03:17:06 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]+)

Euler-Chern correspondence via topological superconductivity
Fan Yang, Xingyu Li, and Chengshu Li
Author(s): Fan Yang, Xingyu Li, and Chengshu Li

The Fermi sea topology is characterized by the Euler characteristic ${χ}_{F}$. In this paper, we examine how ${χ}_{F}$ of the metallic state is inherited by the topological invariant of the superconducting state. We establish a correspondence between the Euler characteristic and the Chern number $C$…

[Phys. Rev. Research 5, 033073] Published Thu Aug 03, 2023

Simple extension of the plane-wave final state in photoemission: Bringing understanding to the photon-energy dependence of two-dimensional materials
Christian S. Kern, Anja Haags, Larissa Egger, Xiaosheng Yang, Hans Kirschner, Susanne Wolff, Thomas Seyller, Alexander Gottwald, Mathias Richter, Umberto De Giovannini, Angel Rubio, Michael G. Ramsey, François C. Bocquet, Serguei Soubatch, F. Stefan Tautz, Peter Puschnig, and Simon Moser
Author(s): Christian S. Kern, Anja Haags, Larissa Egger, Xiaosheng Yang, Hans Kirschner, Susanne Wolff, Thomas Seyller, Alexander Gottwald, Mathias Richter, Umberto De Giovannini, Angel Rubio, Michael G. Ramsey, François C. Bocquet, Serguei Soubatch, F. Stefan Tautz, Peter Puschnig, and Simon Moser

The photoemission cross section of graphene is measured for two light polarizations and a wide range of photon energies at a flux-calibrated synchrotron light source. Modeling scattering effects by a simplistic model and sophisticated time-dependent density-functional-theory calculations, the complex phase shifts in the photoemission final state are extracted from the experiment to obtain complete information about the photoemission process.

[Phys. Rev. Research 5, 033075] Published Thu Aug 03, 2023

Found 1 papers in nano-lett
Date of feed: Thu, 03 Aug 2023 13:05:35 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]+)

[ASAP] Weyl Phonons in Chiral Crystals
Tiantian Zhang, Zhiheng Huang, Zitian Pan, Luojun Du, Guangyu Zhang, and Shuichi Murakami

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Nano Letters
DOI: 10.1021/acs.nanolett.3c02132

Found 3 papers in acs-nano
Date of feed: Thu, 03 Aug 2023 13:02:50 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]+)

[ASAP] Dilute Rhenium Doping and its Impact on Defects in MoS2
Riccardo Torsi, Kyle T. Munson, Rahul Pendurthi, Esteban Marques, Benoit Van Troeye, Lysander Huberich, Bruno Schuler, Maxwell Feidler, Ke Wang, Geoffrey Pourtois, Saptarshi Das, John B. Asbury, Yu-Chuan Lin, and Joshua A. Robinson

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ACS Nano
DOI: 10.1021/acsnano.3c02626

[ASAP] Charging of Vitreous Samples in Cryogenic Electron Microscopy Mitigated by Graphene
Yue Zhang, J. Paul van Schayck, Adrián Pedrazo-Tardajos, Nathalie Claes, Willem E. M. Noteborn, Peng-Han Lu, Hans Duimel, Rafal E. Dunin-Borkowski, Sara Bals, Peter J. Peters, and Raimond B. G. Ravelli

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ACS Nano
DOI: 10.1021/acsnano.3c03722

[ASAP] Wireless Electrical Signals Induce Functional Neuronal Differentiation of BMSCs on 3D Graphene Framework Driven by Magnetic Field
Haoyang Gao, Chunhui Sun, Shuo Shang, Baojun Sun, Mingyuan Sun, Shuang Hu, Hongru Yang, Ying Hu, Zhichao Feng, Weijia Zhou, Chao Liu, Jingang Wang, and Hong Liu

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ACS Nano
DOI: 10.1021/acsnano.3c05725

Found 1 papers in scipost

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Symmetries and topological operators, on average, by Andrea Antinucci, Giovanni Galati, Giovanni Rizi and Marco Serone
< author missing >
Submitted on 2023-08-03, refereeing deadline 2023-09-08.