Found 35 papers in cond-mat
Date of feed: Thu, 16 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)

Qubit fractionalization and emergent Majorana liquid in the honeycomb Floquet code induced by coherent errors and weak measurements. (arXiv:2311.08450v1 [quant-ph])
Guo-Yi Zhu, Simon Trebst

From the perspective of quantum many-body physics, the Floquet code of Hastings and Haah can be thought of as a measurement-only version of the Kitaev honeycomb model where a periodic sequence of two-qubit XX, YY, and ZZ measurements dynamically stabilizes a toric code state with two logical qubits. However, the most striking feature of the Kitaev model is its intrinsic fractionalization of quantum spins into an emergent gauge field and itinerant Majorana fermions that form a Dirac liquid, which is absent in the Floquet code. Here we demonstrate that by varying the measurement strength of the honeycomb Floquet code one can observe features akin to the fractionalization physics of the Kitaev model at finite temperature. Introducing coherent errors to weaken the measurements we observe three consecutive stages that reveal qubit fractionalization (for weak measurements), the formation of a Majorana liquid (for intermediate measurement strength), and Majorana pairing together with gauge ordering (for strong measurements). Our analysis is based on a mapping of the imperfect Floquet code to random Gaussian fermionic circuits (networks) that can be Monte Carlo sampled, exposing two crossover peaks. With an eye on circuit implementations, our analysis demonstrates that the Floquet code, in contrast to the toric code, does not immediately break down to a trivial state under weak measurements, but instead gives way to a long-range entangled Majorana liquid state.

From chiral spin liquids to skyrmion fluids and crystals, and their interplay with itinerant electrons. (arXiv:2311.08468v1 [cond-mat.stat-mech])
F. A. Gómez Albarracín, H. D. Rosales, Masafumi Udagawa, P. Pujol, Ludovic D. C Jaubert

We present an in-depth study of the competition between skyrmions and a chiral spin liquid in a model on the kagome lattice that was recently proposed by some of the authors [H. D. Rosales, et al. Phys. Rev. Lett. 130, 106703 (2023)]. We present an analytical overview of the low-energy states using the Luttinger-Tisza approximation. Then we add thermal fluctuations thanks to large-scale Monte-Carlo simulations, and explore the entire parameter space with a magnetic field $B$, in-plane $D^{xy}$ and out-of-plane $D^z$ Dzyaloshinskii-Moriya interactions, using the ferromagnetic strength as unit of energy. While skyrmions and the chiral spin liquid live in different regions of parameter space, we show how to bring them together, stabilizing a skyrmion fluid in between; a region where the density of well-defined skyrmions can be tuned from quasi-zero (gas) to saturated (liquid) before ordering of the skyrmions (solid). In particular, we investigate the two-dimensional melting of the skyrmion solid. Our analysis also brings to light a long-range ordered phase with Z$_3$ symmetry. To conclude, when conduction electrons are coupled to the local spins, different chiral magnetic textures stabilized in this model (skyrmion solid, liquid and gas \& chiral spin liquid) induce anomalous Quantum Hall effect in the magnetically disordered skyrmion liquid for specific band-filling fractions. Landau levels persist even in the skyrmion-liquid regime in absence of broken translational symmetry and gradually disappear as the skyrmion density decreases to form a gas.

Strongly pinned skyrmionic bubbles and higher-order nonlinear Hall resistances at the interface of Pt/FeSi bilayer. (arXiv:2311.08730v1 [cond-mat.str-el])
T. Hori, N. Kanazawa, K. Matsuura, H. Ishizuka, K. Fujiwara, A. Tsukazaki, M. Ichikawa, M. Kawasaki, F. Kagawa, M. Hirayama, Y. Tokura

Engineering of magnetic heterostructures for spintronic applications has entered a new phase, driven by the recent discoveries of topological materials and exfoliated van der Waals materials. Their low-dimensional properties can be dramatically modulated in designer heterostructures via proximity effects from adjacent materials, thus enabling the realization of diverse quantum states and functionalities. Here we investigate spin-orbit coupling (SOC) proximity effects of Pt on the recently discovered quasi-two-dimensional ferromagnetic state at FeSi surface. Skyrmionic bubbles (SkBs) are formed as a result of the enhanced interfacial Dzyloshinskii-Moriya interaction. The strong pinning effects on the SkBs are evidenced from the significant dispersion in size and shape of the SkBs and are further identified as a greatly enhanced threshold current density required for depinning of the SkBs. The robust integrity of the SkB assembly leads to the emergence of higher-order nonlinear Hall effects in the high current density regime, which originate from nontrivial Hall effects due to the noncollinearity of the spin texture, as well as from the current-induced magnetization dynamics via the augmented spin-orbit torque.

Realization of corner and helical edge states in topologically trivial band gap by twig edge. (arXiv:2311.08733v1 [cond-mat.mes-hall])
Jianfei Li, Ying Wang, Zhongxiang Zhou, Jingfeng Yao, Zhihao Lan, Chengxun Yuan

The twig edge states in graphene-like structures are viewed as the fourth states complementary to their zigzag, bearded, and armchair counterparts. In this work, we study a rod-in-plasma system in honeycomb lattice with twig edges under external magnetic fields and lattice scaling and show that twig edge states can exist in different phases of the system, such as quantum Hall phase, quantum spin Hall phase and insulating phase. The twig edge states in the quantum Hall phase exhibit robust one-way transmission property immune to backscattering and thus provide a novel avenue for solving the plasma communication blackout problem. Moreover, we demonstrate that corner and edge states can exist within the trivial band gap of the insulating phase by modulating the on-site potential of the twig edges. Especially, helical edge states with the unique feature of pseudospin-momentum locking that could be exited by chiral sources are demonstrated at the twig edges within the trivial band gap. Our results show that many topological-like behaviors of electromagnetic waves are not necessarily tied to the exact topology of the systems and the twig edges and interface engineering can bring new opportunities for more flexible manipulation of electromagnetic waves.

Topological Domain-Wall States Hosting Quantized Polarization and Majorana Zero Modes Without Bulk Boundary Correspondence. (arXiv:2311.08771v1 [cond-mat.mes-hall])
Sang-Hoon Han, Myungjun Kang, Moon Jip Park, Sangmo Cheon

Bulk-boundary correspondence is a concept for topological insulators and superconductors that determines the existence of topological boundary states within the tenfold classification table. Contrary to this belief, we demonstrate that topological domain-wall states can emerge in all forbidden 1D classes in the classification table using representative generalized Su-Schrieffer-Heeger and Kitaev models, which manifests as quantized electric dipole moments and Majorana zero modes, respectively. We first show that a zero-energy domain-wall state can possess a quantized polarization, even if the polarization of individual domains is not inherently quantized. A quantized Berry phase difference between the domains confirms the non-trivial nature of the domain-wall states, implying a general-bulk-boundary principle, further confirmed by the tight-binding, topological field, and low-energy effective theories. Our methodology is then extended to a superconducting system, resulting in Majorana zero modes on the domain wall of a generalized Kitaev model. Finally, we suggest potential systems where our results may be realized, spanning from condensed matter to optical.

Strength-dependent Transition of Graphite Under Shock Condition Resolved by First Principles. (arXiv:2311.08805v1 [cond-mat.mtrl-sci])
Gu-Wen Chen, Liang Xu, Yao-Ming Li, Zhi-Pan Liu, Sheng-Cai Zhu

The shock strength dependent formation of diamond represents one of the most intriguing questions in graphite research. Using ab initio DFT-trained carbon GNN model, we observe a strength-dependent graphite transition under shock. The poor sliding caused by scarce sliding time under high-strength shock forms hexagonal diamond with an orientation of (001)G//(100)HD+[010]G//[010]HD; under low-strength shock, cubic diamond forms after enough sliding time, unveiling the strength-dependent graphite transition. We provide computational evidence of the strength-dependent graphite transition from first principles, clarifying the long-term shock-induced hexagonal formation and structural strength-dependent trend source.

A high-efficiency programmable modulator for extreme ultraviolet light with nm feature size based on an electronic phase transition. (arXiv:2311.08809v1 [physics.optics])
Igor Vaskivskyi, Anze Mraz, Rok Venturini, Gregor Jecl, Yevhenii Vaskivskyi, Riccardo Mincigrucci, Laura Foglia, Dario De Angelis, Jacopo-Stefano Pelli-Cresi, Ettore Paltanin, Danny Fainozzi, Filippo Bencivenga, Claudio Masciovecchio, Dragan Mihailovic

The absence of efficient light modulators for extreme ultraviolet (EUV) and X-ray photons significantly limits their real-life application, particularly when even slight complexity of the beam patterns is required. Here we report on a novel approach to reversible imprinting of a holographic mask in an electronic Wigner crystal material with a sub-90 nm feature size. The structure is imprinted on a sub-picosecond time-scale using EUV laser pulses and acts as a high-efficiency diffraction grating that deflects EUV or soft X-ray light. The imprinted nanostructure is stable after the removal of the exciting beams at low temperatures but can be easily erased by a single heating beam. Modeling shows that the efficiency of the device can exceed 1%, approaching state-of-the-art etched gratings, but with the benefit of being programmable and tunable over a large range of wavelengths. The observed effect is based on the rapid change of lattice constant upon transition between metastable electronically-ordered phases in a layered transition metal dichalcogenide. The proposed approach is potentially useful for creating tunable light modulators in the EUV and soft X-ray spectral ranges.

The Anatomy of a Topological Phase Transition in a 2D Chern Insulator. (arXiv:2311.08932v1 [cond-mat.mes-hall])
Arjo Dasgupta, Indra Dasgupta

The onset of the topological phase transition in a two-dimensional model for a Chern Insulator, namely the Qi-Wu-Zhang(QWZ) model, is illustrated, with particular emphasis on the appearance of chiral edge-modes. The edge-modes are studied by analysing the dynamics of the edge-states in an equivalent model for a one-dimensional charge pump, using a technique known as dimensional extension. A further real-space analysis allows us to explain the onset of the topological phase transition in terms of time-reversal symmetry breaking and to quantitatively study the localisation of the edge-modes.

Klein tunneling degradation and enhanced Fabry-P\'erot interference in graphene/h-BN moir\'e-superlattice devices. (arXiv:2311.08938v1 [cond-mat.mes-hall])
Viet-Anh Tran, Viet-Hung Nguyen, Jean-Christophe Charlier

Hexagonal boron-nitride (h-BN) provides an ideal substrate for supporting graphene devices to achieve fascinating transport properties, such as Klein tunneling, electron optics and other novel quantum transport phenomena. However, depositing graphene on h-BN creates moir\'e superlattices, whose electronic properties can be significantly manipulated by controlling the lattice alignment between layers. In this work, the effects of these moir\'e structures on the transport properties of graphene are investigated using atomistic simulations. At large misalignment angles (leading to small moir\'e cells), the transport properties (most remarkably, Klein tunneling) of pristine graphene devices are conserved. On the other hand, in the nearly aligned cases, the moir\'e interaction induces stronger effects, significantly affecting electron transport in graphene. In particular, Klein tunneling is significantly degraded. In contrast, strong Fabry-P\'erot interference (accordingly, strong quantum confinement) effects and non-linear I-V characteristics are observed. P-N interface smoothness engineering is also considered, suggesting as a potential way to improve these transport features in graphene/h-BN devices.

Tailoring the defects and electronic band structure in WS2/h-BN heterostructure. (arXiv:2311.08948v1 [cond-mat.mes-hall])
Suvodeep Paul, Saheb Karak, Saswata Talukdar, Devesh Negi, Surajit Saha

The 2D semiconducting transition metal dichalcogenides (e.g., WS2) host strong coupling between various degrees of freedom leading to potential applications in next-generation device applications including optoelectronics. Such applications are strongly influenced by defects which can control both the optical and electronic properties of the material. We demonstrate the possibility to tailor the defect-related electronic states and the lattice dynamics properties of WS2 in their heterostructures with h-BN which host a strong interlayer coupling between the charge carriers in the WS2 layer and the phonons of h-BN. This coupling is observed to induce modifications to the interlayer phonons (manifested by their modified Raman-activity) and to the charge carrier mobilities in the WS2 layer (which results in creation of mid-gap energy states associated with many-body quasiparticle states). Our study also includes a detailed characterization of the defects through Raman measurements revealing an A_1g-type nature with differential resonance behavior for the modes that are related to defect scattering with respect to the other normal phonon modes of WS2.

Hall-effect in the MnBi_2Te_4 crystal using silicon nitride nanomembrane via contacts. (arXiv:2311.08953v1 [cond-mat.mtrl-sci])
Mickey Martini, Tommaso Confalone, Yejin Lee, Bastian Rubrecht, Giuseppe Serpico, Sanaz Shokri, Christian N. Saggau, Domenico Montemurro, Valerii M. Vinokur, Anna Isaeva, Kornelius Nielsch, Nicola Poccia

Utilizing an interplay between band topology and intrinsic magnetism, the two-dimensional van der Waals (vdW) system MnBi_2Te_4 provides an ideal platform for realizing exotic quantum phenomena and offers great opportunities in the emerging field of antiferromagnetic spintronic technology. Yet, the fabrication of MnBi_2Te_4-based nanodevices is hindered by the high sensitivity of this material, which quickly degrades when exposed to air or to elevated temperatures. Here, we demonstrate an alternative route of fabricating vdW-MnBi_2Te_4-based electronic devices using the cryogenic dry transfer of a printable circuit embedded in an inorganic silicon nitride membrane. The electrical connections between the thin crystal and the top surface of the membrane are established through via contacts. Our magnetotransport study reveals that this innovative via contact approach enables exploring the MnBi_2Te_4-like sensitive 2D materials and engineering synthetic heterostructures as well as complex circuits based on the two-dimensional vdW systems.

Transport theory in non-Hermitian systems. (arXiv:2311.08973v1 [cond-mat.mes-hall])
Qing Yan, Hailong Li, Qing-Feng Sun, X. C. Xie

Non-Hermitian systems have garnered significant attention due to the emergence of novel topology of complex spectra and skin modes. However, investigating transport phenomena in such systems faces obstacles stemming from the non-unitary nature of time evolution. Here, we establish the continuity equation for a general non-Hermitian Hamiltonian in the Schr\"odinger picture. It attributes the universal non-conservativity to the anti-commutation relationship between particle number and non-Hermitian terms. Our work derives a comprehensive current formula for non-Hermitian systems using Green's function, applicable to both time-dependent and steady-state responses. To demonstrate the validity of our approach, we calculate the local current in models with one-dimensional and two-dimensional settings, incorporating scattering potentials. The spatial distribution of local current highlights the widespread non-Hermitian phenomena, including skin modes, non-reciprocal quantum dots, and corner states. Our findings offer valuable insights for advancing theoretical and experimental research in the transport of non-Hermitian systems.

Transport properties of strongly correlated Fermi systems. (arXiv:2311.08974v1 [cond-mat.str-el])
V.R. Shaginyan, A.Z. Msezane, M.V. Zverev

In our short review, we consider the transport properties of strongly correlated Fermi systems like heavy fermion metals and high-$T_c$ superconductors. Their transport properties are defined by strong inter-particle interaction forming flat bands in these compounds. Indeed, in contrast to the behavior of the transport properties of conventional metals, the strongly correlated compounds exhibit the linear in temperature resistivity, $\rho(T)\propto T$. We analyze the magnetoresistance and show that it under the application of magnetic field becomes negative. It is shown that near a quantum phase transition, when the density of electronic states diverges, semiclassical physics remains applicable to describe the resistivity $\rho$ of strongly correlated metals due to the presence of a transverse zero-sound collective mode, representing the phonon mode in solids. We demonstrate that when $T$ exceeds the extremely low Debye temperature $T_D$, the resistivity $\rho(T)$ changes linearly with $T$, since the mechanism of formation of the $T$-dependence $\rho(T)$ is similar electron-phonon mechanism, which predominates at high temperatures in ordinary metals. Thus, in the region of $T$-linear resistance, electron-phonon scattering leads to a lifetime of $\tau$ quasiparticles practically independent of the material, which is expressed as the ratio of the Planck constant $\hbar$ to the Boltzmann constant constant $k_B$, $T\tau\sim \hbar/k_B$. We explain that due to the non-Fermi-liquid behavior the real part of the frequency-dependent optical conductivity $\sigma^R_{opt}(\omega)$ exhibits a scaling behavior, and demonstrates the unusual power law behavior $\sigma^R_{opt}(\omega)\propto\omega^{-1}$, rather than the well-known one shown by conventional metals, $\sigma^R_{opt}(\omega)\propto\omega^{-2}$.

Thickness dependent mechanical properties of soft ferromagnetic two-dimensional CoTe2. (arXiv:2311.08994v1 [cond-mat.mtrl-sci])
Surbhi Slathia, Cencen Wei, Manoj Tripathi, Raphael Tromer, Solomon Demiss Negedu, Conor Boland, Suman Sarkar, Douglas S. Galvao, Alan Dalton, Chandra Sekhar Tiwary

Two dimensional (2D) layered transition-metal-based tellurides (chalcogens) are known to harness their surface atoms characteristics to enhance topographical activities for energy conversion, storage, and magnetic applications. High surface energy due to unsaturated dangling bonds and larger lateral size than the thickness (volume) makes them a potential candidate for emerging electronics. Nevertheless, the gradual stacking of each sheet alters the surface atoms' subtle features, such as lattice expansion, leading to several phenomena and rendering tunable properties. In the present work, we have monitored thickness-dependent properties of the 2D CoTe2 sheets from nanoscale mechanics, tribology, surface potential distributions, interfacial interaction and magnetism using atomically resolved spectroscopy and different surface probe techniques, in conjunction with theoretical investigations: density functional theory (DFT) and molecular dynamics (MD). The variation in properties observed in theoretical investigation unleashes the crucial role of crystal planes of the CoTe2. The presented results are beneficial in expanding the use of 2D telluride family in flexible electronics, piezo sensors, tribo-generator, and next-generation memory devices.

Josephson Diode Effect in Topological Superconductor. (arXiv:2311.09009v1 [cond-mat.supr-con])
Zhaochen Liu, Linghao Huang, Jing Wang

We investigate the Josephson diode effect in topological Josephson junctions. We find that while a Josephson junction in the topological phase may exhibit higher diode efficiency compared to that in the trivial phase, this behavior is not universal. The presence of Majorana bound states is not a sufficient condition for a large diode effect. Furthermore, the diode efficiency undergoes substantial changes only in specific regions along the topological phase transition boundary, and a significant diode effect does coincide with the topological phases. Thereby the Josephson diode effect may be serves as a weak indicator for topological superconductor phase. These results suggest a nuanced relationship between the topological aspects of Josephson junctions and Josephson diode effect.

Metal-free Stoner and Mott-Hubbard magnetism in 2D polymers with honeycomb lattice. (arXiv:2311.09026v1 [cond-mat.str-el])
Hongde Yu, Thomas Heine

We computationally demonstrate Stoner-ferromagnetic half-metals and antiferromagnetic Mott-Hubbard insulators in metal-free 2D polymers. Coupling radicaloid (hetero)triangulene monomers via strong covalent bonds preserving the in-plane conjugation of the electronic {\pi} system yields 2D crystals with long-range magnetic order and magnetic couplings above the Landauer limit. Dual-site honeycomb lattices produce both flat bands and Dirac cones. Depending on the monomers, electron correlations lead to either a bandgap at the Dirac points for antiferromagnetic Mott insulators, or Stoner ferromagnetism with both spin-polarized Dirac cones and flat bands at the Fermi level. These results pioneer a new type of Stoner and Mott-Hubbard magnetism emerging in the electronic pi system of crystalline conjugated 2D polymers.

Electronic structure in a transition metal dipnictide TaAs2. (arXiv:2311.09055v1 [cond-mat.mes-hall])
Sabin Regmi, Cheng-Yi Huang, Mojammel A. Khan, Baokai Wang, Anup Pradhan Sakhya, M. Mofazzel Hosen, Jesse Thompson, Bahadur Singh, Jonathan D. Denlinger, Masahiro Ishigami, J.F. Mitchell, Dariusz Kaczorowski, Arun Bansil, Madhab Neupane

The family of transition metal dipnictides (TMDs) has been of theoretical and experimental interest because this family hosts topological states and extremely large magnetoresistance (MR). Recently, TaAs2, a member of this family, has been predicted to support a topological crystalline insulating state. Here, by using high resolution. Angle resolved photoemission spectroscopy (ARPES), we reveal both closed and open pockets in the metallic Fermi surface and linearly dispersive bands on the (201) surface, along with the presence of extreme MR observed from magneto-transport measurements. A comparison of the ARPES results with first-principles computations show that the linearly dispersive bands on the measured surface of TaAs2 are trivial bulk bands. The absence of symmetry-protected surface state on the (201) surface indicates its topologically dark nature. The presence of open Fermi surface features suggests that the open orbit fermiology could contribute to the extremely large MR of TaAs.

Ultrathick MA$_2$N$_4$(M'N) Intercalated Monolayers with Sublayer-Protected Fermi Surface Conduction States: Interconnect and Metal Contact Applications. (arXiv:2311.09057v1 [cond-mat.mtrl-sci])
Che Chen Tho, Xukun Feng, Zhuoling Jiang, Liemao Cao, Chit Siong Lau, San-Dong Guo, Yee Sin Ang

Recent discovery of ultrathick $\mathrm{MoSi_2N_4(MoN)_n}$ monolayers open up an exciting platform to engineer 2D material properties via intercalation architecture. Here we computationally investigate a series of ultrathick MA$_2$N$_4$(M'N) monolayers (M, M' = Mo, W; A = Si, Ge) under both homolayer and heterolayer intercalation architectures in which the same and different species of transition metal nitride inner core layers are intercalated by outer passivating nitride sublayers, respectively. The MA$_2$N$_4$(M'N) monolayers are thermally, dynamically and mechanically stable with excellent mechanical strength and metallic properties. Intriguingly, the metallic states around Fermi level are localized within the inner core layers. Carrier conduction mediated by electronic states around the Fermi level is thus spatially insulated from the external environment by the native outer nitride sublayers, suggesting the potential of MA$_2$N$_4$(M'N) in back-end-of-line (BEOL) metal interconnect applications. Nitrogen vacancy defect at the outer sublayers creates `punch through' states around the Fermi level that bridges the carrier conduction in the inner core layers and the outer environment, forming a electrical contact akin to the `vias' structures of metal interconnects. We further show that MoSi$_2$N$_4$(MoN) can serve as a quasi-Ohmic contact to 2D WSe$_2$. These findings reveal the promising potential of ultrathick MA$_2$N$_4$(MN) monolayers as metal electrodes and BEOL interconnect applications.

Single pair of charge-two high-fold fermions in ultralight chiral crystals. (arXiv:2311.09070v1 [cond-mat.mtrl-sci])
Xiaoliang Xiao, Yuanjun Jin, Da-Shuai Ma, Haoran Wei, Jing Fan, Rui Wang, Xiaozhi Wu

The realization of single-pair chiral fermions in Weyl systems remains challenging in topology physics, especially for the systems with higher chiral charges $|C|$. In this work, based on the symmetry analysis and low-energy effective model, we propose that single-pair high-fold topological fermions with $C$ = $\pm{2}$ can be achieved in chiral space groups P2$_1$3, P4$_3$32, and P4$_1$32. Here, a single pair of Weyl points with the oppositely chiral charges of $|C| = 2$ has been proved by the minimal lattice model and shows the unique characteristics compared to multi-pair Weyl fermionic systems, including the larger nontrivial energy window and the ultralong double Fermi arcs extended to the whole Brillouin zone. Furthermore, we show the first ultralight chiral crystal P4$_3$32-type LiC$_2$ and its inversion enantiomer as high-quality candidate materials, whose Weyl nodes exhibit the large linear energy range to surmount the interruption of irrelevant bands, and we observe a reversal of their Fermi-arc velocities. Our work not only provides a promising platform for detecting ultralong chiral fermi arcs but also certainly leads to continued exploration of unconventional fermions.

Broad-Wavevector Spin Pumping of Flat-Band Magnons. (arXiv:2311.09098v1 [cond-mat.mes-hall])
Jinlong Wang, Hanchen Wang, Jilei Chen, William Legrand, Peng Chen, Lutong Sheng, Jihao Xia, Guibin Lan, Yuelin Zhang, Rundong Yuan, Jing Dong, Xiufeng Han, Jean-Philippe Ansermet, Haiming Yu

We report the experimental observation of large spin pumping signals in YIG/Pt system driven by broad-wavevector spin-wave spin current. 280 nm-wide microwave inductive antennas offer broad-wavevector excitation which, in combination with quasi-flatband of YIG, allows a large number of magnons to participate in spin pumping at a given frequency. Through comparison with ferromagnetic resonance spin pumping, we attribute the enhancement of the spin current to the multichromatic magnons. The high efficiency of spin current generation enables us to uncover nontrivial propagating properties in ultra-low power regions. Additionally, our study achieves the spatially separated detection of magnons, allowing the direct extraction of the decay length. The synergistic combination of the capability of broad-wavevector excitation, enhanced voltage signals, and nonlocal detection provides a new avenue for the electrical exploration of spin waves dynamics.

Stability of topologically protected slow light against disorder. (arXiv:2311.09220v1 [physics.optics])
Jonas F. Karcher, Sarang Gopalakrishnan, Mikael C. Rechtsman

Slowing down light in on-chip photonic devices strongly enhances light-matter interaction, but typically also leads to increased backscattering and small-bandwidth operation. It was shown re- cently that, if one modifies the edge termination of a photonic Chern insulator such that the edge mode wraps many times around the Brillouin zone, light can be slowed to arbitrarily low group velocity over a large bandwidth, without being subject to backscattering. Here we study the robust- ness of these in-gap slow light modes against fabrication disorder, finding that disorder on scales significantly larger than the minigaps between edge bands is tolerable. We identify the mechanism for wavepacket breakup as disorder-induced velocity renormalization and calculate the associated breakup time.

Monolayer Kagome Metals AV$_3$Sb$_5$. (arXiv:2202.11521v2 [cond-mat.str-el] UPDATED)
Sun-Woo Kim, Hanbit Oh, Eun-Gook Moon, Youngkuk Kim

Recently, layered kagome metals AV$_3$Sb$_5$ (A = K, Rb, and Cs) have emerged as a fertile platform for exploring frustrated geometry, correlations, and topology. Here, using first-principles and mean-field calculations, we demonstrate that AV$_3$Sb$_5$ can crystallize in a mono-layered form, revealing a range of properties that render the system unique. Most importantly, the two-dimensional monolayer preserves intrinsically different symmetries from the three-dimensional layered bulk, enforced by stoichiometry. Consequently, the van Hove singularities, logarithmic divergences of electronic density of states, are enriched, leading to a variety of competing instabilities such as doublets of charge density waves and s-and d-wave superconductivity. We show that the competition between orders can be fine-tuned in the monolayer via electron-filling of the van Hove singularities. Thus, our results suggest the monolayer kagome metal AV$_3$Sb$_5$ as a promising platform for designer quantum phases.

Replica Higher-Order Topology of Hofstadter Butterflies in Twisted Bilayer Graphene. (arXiv:2204.08087v2 [cond-mat.mes-hall] UPDATED)
Sun-Woo Kim, Sunam Jeon, Moon Jip Park, Youngkuk Kim

The Hofstadter energy spectrum of twisted bilayer graphene is found to have recursive higher-order topological properties. We demonstrate that higher-order topological insulator (HOTI) phases, characterized by localized corner states, occur as replicas of the original HOTIs to fulfill the self-similarity of the Hofstadter spectrum. We show the existence of the exact flux translational symmetry of twisted bilayer graphene at all commensurate angles. Based on this result, we carefully identify that the original HOTI phase at zero flux is re-entrant at a half-flux periodicity, where the effective twofold rotation is preserved. In addition, numerous replicas of the original HOTIs are found for fluxes without protecting symmetries. Similar to the original HOTIs, replica HOTIs feature both localized corner states and edge-localized real-space topological markers. The replica HOTIs originate from the different interaction scales, namely, intralayer and interlayer couplings, in twisted bilayer graphene. The topological aspect of Hofstadter butterflies revealed in our results highlights symmetry-protected topology in quantum fractals.

Advances in honeycomb layered oxides: Part I -- Syntheses and Characterisations of Pnictogen- and Chalcogen-Based Honeycomb Layered Oxides. (arXiv:2207.06499v4 [cond-mat.mtrl-sci] UPDATED)
Godwill Mbiti Kanyolo, Titus Masese, Abbas Alshehabi, Zhen-Dong Huang

Advancements in nanotechnology continue to unearth material vistas that presage a new age of revolutionary functionalities replete with unparalleled physical properties and avant-garde chemical capabilities that promise sweeping paradigm shifts in energy, environment, telecommunications and potentially healthcare. At the upper echelons of this realm, the pnictogen and chalcogen class of honeycomb layered oxides have emerged with fascinating crystal chemistry and exotic electromagnetic and topological phenomena that muster multifaceted concepts spanning from materials science to condensed matter physics and potential applications in electrochemistry, quantum mechanics and electronics. In a bid to shed light on the mechanisms governing these biomimetic nanostructures, this review highlights the significant milestones and breakthroughs that have augmented their current fundamental theory, properties, and utilities. Herein, we elucidate the vast promising crystal chemistry space against the backdrop of known synthesis and characterisation techniques employed in the development and optimisation of this class of honeycomb layered oxides. Further, we highlight key theoretical models that have reinvigorated the exploration and characterisation of within this class of materials and are poised to redefine the frontiers of material research and their applications. We conclude by envisaging future research directions where fascinating physicochemical, topological and electromagnetic properties could be lurking and where valiant efforts ought to be inclined, particularly in the prospective realisation of exotic material compositional space as well as their utility as testing grounds for emergent two-dimensional (2D) topological quantum gravity and conformal field theories.

Light-driven C-H bond activation mediated by 2D transition metal dichalcogenides. (arXiv:2208.07902v2 [cond-mat.mtrl-sci] UPDATED)
Jingang Li, Di Zhang, Zhongyuan Guo, Xi Jiang, Jonathan M. Larson, Haoyue Zhu, Tianyi Zhang, Yuqian Gu, Brian Blankenship, Min Chen, Zilong Wu, Suichu Huang, Robert Kostecki, Andrew M. Minor, Costas P. Grigoropoulos, Deji Akinwande, Mauricio Terrones, Joan M. Redwing, Hao Li, Yuebing Zheng

C-H bond activation enables the facile synthesis of new chemicals. While C-H activation in short-chain alkanes has been widely investigated, it remains largely unexplored for long-chain organic molecules. Here, we report light-driven C-H activation in complex organic materials mediated by 2D transition metal dichalcogenides (TMDCs) and the resultant solid-state synthesis of luminescent carbon dots in a spatially-resolved fashion. We unravel the efficient H adsorption and a lowered energy barrier of C-C coupling mediated by 2D TMDCs to promote C-H activation. Our results shed light on 2D materials for C-H activation in organic compounds for applications in organic chemistry, environmental remediation, and photonic materials.

Interaction-driven topological phase diagram of twisted bilayer MoTe$_2$. (arXiv:2305.01006v3 [cond-mat.mes-hall] UPDATED)
Wen-Xuan Qiu, Bohao Li, Xun-Jiang Luo, Fengcheng Wu

Twisted bilayer MoTe$_2$ is a promising platform to investigate the interplay between band topology and many-body interaction. We present a theoretical study of its interaction-driven quantum phase diagrams based on a three-orbital model, which can be viewed as a generalization of the Kane-Mele-Hubbard model with one additional orbital and long-range Coulomb repulsion. We predict a cascade of phase transitions tuned by the twist angle $\theta$. At the hole filling factor $\nu=1$ (one hole per moir\'e unit cell), the ground state can be in the multiferroic phase with coexisting spontaneous layer polarization and magnetism, the quantum anomalous Hall phase, and finally the topologically trivial magnetic phases, as $\theta$ increases from $1.5^{\circ}$ to $5^{\circ}$. At $\nu=2$, the ground state can have a second-order phase transition between an antiferromagnetic phase and the quantum spin Hall phase as $\theta$ passes through a critical value. The dependence of the phase boundaries on model parameters such as the gate-to-sample distance, the dielectric constant, and the moir\'e potential amplitude is examined. The predicted phase diagrams can guide the search for topological phases in twisted transition metal dichalcogenide homobilayers.

Sub-100 nm {\beta}-Ga2O3 MOSFET with 55 GHz fMAX and >100 V breakdown. (arXiv:2305.04725v2 [cond-mat.mtrl-sci] UPDATED)
Chinmoy Nath Saha, Abhishek Vaidya, A F M Anhar Uddin Bhuiyan, Lingyu Meng, Hongping Zhao, Uttam Singisetti

This letter reports a highly scaled 90 nm gate length beta-Ga2O3 T-gate MOSFET with no current collapse and record power gain cut off frequency (fMAX). The epitaxial stack of 60 nm thin channel MOSFET was grown by Molecular Beam Epitaxy (MBE) and highly doped (n++) contact regrowth was carried out by Metal Organic Chemical Vapour Deposition (MOCVD) in the source/drain region. Maximum on current (IDS, MAX) of 160 mA/mm and transconductance (gm) around 36 mS/mm was measured at VDS= 10 V for LSD= 1.5 micrometer channel length. Transconductance is limited by higher channel sheet resistance (Rsheet). We observed no current collapse for both drain and gate lag measurement even at higher VDG,Q quiescent bias points. This is the first report of Ga2O3 FET showing no current collapse without any external passivation. Breakdown voltage around 125 V was reported for LGD= 1.2 micrometer. We extracted 27 GHz current gain cut off frequency (fT) and 55 GHz fMAX for 20 V drain bias. fMAX value mentioned here is the highest for Ga2O3 and the first demonstration of 55 GHz operation. fT. VBR product of 3.375 THz.V has been calculated which is comparable with state-of-art GaN HEMT. This letter suggests that Ga2O3 can be a suitable candidate for X-band application.

Vortex line entanglement in active Beltrami flows. (arXiv:2306.01062v2 [physics.flu-dyn] UPDATED)
Nicolas Romeo, Jonasz Slomka, Jorn Dunkel, Keaton J. Burns

Over the last decade, substantial progress has been made in understanding the topology of quasi-2D non-equilibrium fluid flows driven by ATP-powered microtubules and microorganisms. By contrast, the topology of 3D active fluid flows still poses interesting open questions. Here, we study the topology of a spherically confined active flow using 3D direct numerical simulations of generalized Navier-Stokes (GNS) equations at the scale of typical microfluidic experiments. Consistent with earlier results for unbounded periodic domains, our simulations confirm the formation of Beltrami-like bulk flows with spontaneously broken chiral symmetry in this model. Furthermore, by leveraging fast methods to compute linking numbers, we explicitly connect this chiral symmetry breaking to the entanglement statistics of vortex lines. We observe that the mean of linking number distribution converges to the global helicity, consistent with the asymptotic result by Arnold. Additionally, we characterize the rate of convergence of this measure with respect to the number and length of observed vortex lines, and examine higher moments of the distribution. We find that the full distribution is well described by a k-Gamma distribution, in agreement with an entropic argument. Beyond active suspensions, the tools for the topological characterization of 3D vector fields developed here are applicable to any solenoidal field whose curl is tangent to or cancels at the boundaries in a simply connected domain.

Tunable non-additivity in Casimir-Lifshitz force between graphene gratings. (arXiv:2306.17640v2 [cond-mat.mes-hall] UPDATED)
Youssef Jeyar, Minggang Luo, Kevin Austry, Brahim Guizal, Yi Zheng, H. B. Chan, Mauro Antezza

We investigate the Casimir-Lifshitz force (CLF) between two identical graphene strip gratings, laid on finite dielectric substrates, by using the scattering matrix (S-matrix) approach derived from the Fourier Modal Method with Local Basis Functions (FMM-LBF). We fully take into account the high-order electromagnetic diffractions, the multiple scattering and the exact 2D feature of the graphene strips. We show that the non-additivity, which is one of the most interesting features of the CLF in general, is significantly high and can be modulated in situ, without any change in the actual material geometry and this by varying the graphene chemical potential. We discuss the nature of the geometrical effects and show the relevance of the geometric parameter d/D (i.e. the ratio between separation and grating period), which allows to explore the regions of parameters where the additive result is fully acceptable or where the full calculation is needed. This study can open to deeper experimental exploration of the non-additive features of the CLF with micro- or nano-electromechanical graphene-based systems.

Topological interface states -- a possible path towards a Landau-level laser in the THz regime. (arXiv:2307.05116v3 [cond-mat.mes-hall] UPDATED)
Mark O. Goerbig

Volkov-Pankratov surface bands arise in smooth topological interfaces, i.e. interfaces between a topological and a trivial insulator, in addition to the chiral surface state imposed by the bulk-surface correspondence of topological materials. These two-dimensional bands become Landau-quantized if a magnetic field is applied perpendicular to the interface. I show that the energy scales, which are typically in the 10-100 meV range, can be controlled both by the perpendicular magnetic field and the interface width. The latter can still be varied with the help of a magnetic-field component in the interface. The Landau levels of the different Volkov-Pankratov bands are optically coupled, and their arrangement may allow one to obtain population inversion by resonant optical pumping. This could serve as the elementary brick of a multi-level laser based on Landau levels. Moreover, the photons are absorbed and emitted either parallel or perpendicular to the magnetic field, respectively in the Voigt and Faraday geometry, depending on the Volkov-Pankratov bands and Landau levels involved in the optical transitions.

Correlation-induced phase transitions and mobility edges in an interacting non-Hermitian quasicrystal. (arXiv:2310.01275v2 [quant-ph] UPDATED)
Tian Qian, Yongjian Gu, Longwen Zhou

Non-Hermitian quasicrystal constitutes a unique class of disordered open system with PT-symmetry breaking, localization and topological triple phase transitions. In this work, we uncover the effect of quantum correlation on phase transitions and entanglement dynamics in non-Hermitian quasicrystals. Focusing on two interacting bosons in a Bose-Hubbard lattice with quasiperiodically modulated gain and loss, we find that the onsite interaction between bosons could drag the PT and localization transition thresholds towards weaker disorder regions compared with the noninteracting case. Moreover, the interaction facilitates the expansion of the critical point of a triple phase transition in the noninteracting system into a critical phase with mobility edges, whose domain could be flexibly controlled by tuning the interaction strength. Systematic analyses of the spectrum, inverse participation ratio, topological winding number, wavepacket dynamics and entanglement entropy lead to consistent predictions about the correlation-driven phases and transitions in our system. Our findings pave the way for further studies of the interplay between disorder and interaction in non-Hermitian quantum matter.

Experimental signatures of quantum and topological states in frustrated magnetism. (arXiv:2310.15071v2 [cond-mat.str-el] UPDATED)
J. Khatua, B. Sana, A. Zorko, M. Gomilšek, K. Sethupathi M. S. Ramachandra Rao, M. Baenitz, B. Schmidt, P. Khuntia

Frustration in magnetic materials arising from competing exchange interactions can prevent the system from adopting long-range magnetic order and can instead lead to a diverse range of novel quantum and topological states with exotic quasiparticle excitations. Here, we review prominent examples of such emergent phenomena, including magnetically-disordered and extensively degenerate spin ices, which feature emergent magnetic monopole excitations, highly-entangled quantum spin liquids with fractional spinon excitations, topological order and emergent gauge fields, as well as complex particle-like topological spin textures known as skyrmions. We provide an overview of recent advances in the search for magnetically-disordered candidate materials on the three-dimensional pyrochlore lattice and two-dimensional triangular, kagome and honeycomb lattices, the latter with bond-dependent Kitaev interactions, and on lattices supporting topological magnetism. We highlight experimental signatures of these often elusive phenomena and single out the most suitable experimental techniques that can be used to detect them. Our review also aims at providing a comprehensive guide for designing and investigating novel frustrated magnetic materials, with the potential of addressing some important open questions in contemporary condensed matter physics.

Engineering the Kitaev spin liquid in a quantum dot system. (arXiv:2310.18393v2 [cond-mat.mes-hall] UPDATED)
Tessa Cookmeyer, Sankar Das Sarma

The Kitaev model on a honeycomb lattice may provide a robust topological quantum memory platform, but finding a material that realizes the unique spin liquid phase remains a considerable challenge. We demonstrate that an effective Kitaev Hamiltonian can arise from a half-filled Fermi-Hubbard Hamiltonian where each site can experience a magnetic field in a different direction. As such, we provide a method for realizing the Kitaev spin liquid on a single hexagonal plaquette made up of twelve quantum dots. Despite the small system size, there are clear signatures of the Kitaev spin-liquid ground state, and there is a range of parameters where these signatures are predicted, allowing a potential platform where Kitaev spin-liquid physics can be explored experimentally in quantum dot plaquettes.

Dynamical characterization of $Z_{2}$ Floquet topological phases via quantum quenches. (arXiv:2311.00114v2 [cond-mat.quant-gas] UPDATED)
Lin Zhang

The complete characterization of a generic $d$-dimensional Floquet topological phase is usually hard for the requirement of information about the micromotion throughout the entire driving period. In a recent work [L. Zhang et al., Phys. Rev. Lett. 125, 183001 (2020)], an experimentally feasible dynamical detection scheme was proposed to characterize the integer Floquet topological phases using quantum quenches. However, this theory is still far away from completion, especially for free-fermion Floquet topological phases, where the states can also be characterized by $Z_{2}$ invariants. Here we develop the first full and unified dynamical characterization theory for the $Z_{2}$ Floquet topological phases of different dimensionality and tenfold-way symmetry classes by quenching the system from a trivial and static initial state to the Floquet topological regime through suddenly changing the parameters and turning on the periodic driving. By measuring the minimal information of Floquet bands via the stroboscopic time-averaged spin polarizations, we show that the topological spin texture patterns emerging on certain discrete momenta of Brillouin zone called the $0$ or $\pi$ gap highest-order band-inversion surfaces provide a measurable dynamical $Z_{2}$ Floquet invariant, which uniquely determines the Floquet boundary modes in the corresponding quasienergy gap and characterizes the $Z_{2}$ Floquet topology. The applications of our theory are illustrated via one- and two-dimensional models that are accessible in current quantum simulation experiments. Our work provides a highly feasible way to detect the $Z_{2}$ Floquet topology and completes the dynamical characterization for the full tenfold classes of Floquet topological phases, which shall advance the research in theory and experiments.

Valley-hybridized gate-tunable 1D exciton confinement in MoSe2. (arXiv:2311.05299v2 [cond-mat.mes-hall] UPDATED)
Maximilian Heithoff, Álvaro Moreno, Iacopo Torre, Matthew S. G. Feuer, Carola M. Purser, Gian Marcello Andolina, Giuseppe Calajo, Kenji Watanabe, Takashi Taniguchi, Dhiren Kara, Patrick Hays, Sefaattin Tongay, Vladimir Falko, Darrick Chang, Mete Atatüre, Antoine Reserbat-Plantey, Frank Koppens

Controlling excitons at the nanoscale in semiconductor materials represents a formidable challenge in the fields of quantum photonics and optoelectronics. Achieving this control holds great potential for unlocking strong exciton-exciton interaction regimes, enabling exciton-based logic operations, exploring exotic quantum phases of matter, facilitating deterministic positioning and tuning of quantum emitters, and designing advanced optoelectronic devices. Monolayers of transition metal dichalcogenides (TMDs) offer inherent two-dimensional confinement and possess significant binding energies, making them particularly promising candidates for achieving electric-field-based confinement of excitons without dissociation. While previous exciton engineering strategies have predominantly focused on local strain gradients, the recent emergence of electrically confined states in TMDs has paved the way for novel approaches. Exploiting the valley degree of freedom associated with these confined states further broadens the prospects for exciton engineering. Here, we show electric control of light polarization emitted from one-dimensional (1D) quantum confined states in MoSe2. By employing non-uniform in-plane electric fields, we demonstrate the in-situ tuning of the trapping potential and reveal how gate-tunable valley-hybridization gives rise to linearly polarized emission from these localized states. Remarkably, the polarization of the localized states can be entirely engineered through either the spatial geometry of the 1D confinement potential or the application of an out-of-plane magnetic field.

Found 8 papers in prb
Date of feed: Thu, 16 Nov 2023 04:17:16 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)

Rich magnetic phase diagram of putative helimagnet ${\text{Sr}}_{3}{\text{Fe}}_{2}{\text{O}}_{7}$
Nikita D. Andriushin, Justus Grumbach, Jung-Hwa Kim, Manfred Reehuis, Yuliia V. Tymoshenko, Yevhen A. Onykiienko, Anil Jain, W. Andrew MacFarlane, Andrey Maljuk, Sergey Granovsky, Andreas Hoser, Vladimir Pomjakushin, Jacques Ollivier, Mathias Doerr, Bernhard Keimer, Dmytro S. Inosov, and Darren C. Peets
Author(s): Nikita D. Andriushin, Justus Grumbach, Jung-Hwa Kim, Manfred Reehuis, Yuliia V. Tymoshenko, Yevhen A. Onykiienko, Anil Jain, W. Andrew MacFarlane, Andrey Maljuk, Sergey Granovsky, Andreas Hoser, Vladimir Pomjakushin, Jacques Ollivier, Mathias Doerr, Bernhard Keimer, Dmytro S. Inosov, and Darren C. Peets

The cubic perovskite ${\text{SrFeO}}_{\text{3}}$ was recently reported to host hedgehog- and skyrmion-lattice phases in a highly symmetric crystal structure which does not support the Dzyaloshinskii-Moriya interactions commonly invoked to explain such magnetic order. Hints of a complex magnetic phas…

[Phys. Rev. B 108, 174420] Published Wed Nov 15, 2023

Edge and corner skin effects of chirally coupled magnons characterized by a topological winding tuple
Chengyuan Cai, Dante M. Kennes, Michael A. Sentef, and Tao Yu
Author(s): Chengyuan Cai, Dante M. Kennes, Michael A. Sentef, and Tao Yu

We investigate a long-ranged coupled and non-Hermitian two-dimensional array of nanomagnets, fabricated on a thin magnetic substrate and subjected to an in-plane magnetic field. We predict topology-driven edge and corner skin effects of magnetic eigenmodes with the localization position at boundarie…

[Phys. Rev. B 108, 174421] Published Wed Nov 15, 2023

Information trapping by topologically protected edge states: Scrambling and the butterfly velocity
Martyna Sedlmayr, Hadi Cheraghi, and Nicholas Sedlmayr
Author(s): Martyna Sedlmayr, Hadi Cheraghi, and Nicholas Sedlmayr

Topological insulators and superconductors have recently attracted considerable attention, and many different theoretical tools have been used to gain insight into their properties. Here we investigate how perturbations can spread through exemplary one-dimensional topological insulators and supercon…

[Phys. Rev. B 108, 184303] Published Wed Nov 15, 2023

Layer number dependent spin Hall effects in transition metal monocarbides ${M}_{2}\mathrm{C} (M=\mathrm{V},\mathrm{Nb},\mathrm{Ta})$
Xi Zuo, Yulin Feng, Na Liu, Bing Huang, Meifeng Liu, Desheng Liu, and Bin Cui
Author(s): Xi Zuo, Yulin Feng, Na Liu, Bing Huang, Meifeng Liu, Desheng Liu, and Bin Cui

The recent discovery of strong spin Hall effects (SHEs) in two-dimensional layered topological semimetals has attracted intensive attention due to their exotic electronic properties and potential applications in spintronic devices. In this paper, we systematically study the topological properties an…

[Phys. Rev. B 108, 195129] Published Wed Nov 15, 2023

Kondo breakdown in the topological Kondo insulator $\mathrm{Sm}{\mathrm{B}}_{6}$ studied by point-contact Andreev reflection spectroscopy
Masanobu Shiga, Tsubasa Teramoto, Takurou Harada, Takuya Takahashi, Fumitoshi Iga, and Tatsuya Kawae
Author(s): Masanobu Shiga, Tsubasa Teramoto, Takurou Harada, Takuya Takahashi, Fumitoshi Iga, and Tatsuya Kawae

We studied the topological features in Kondo insulator $\mathrm{Sm}{\mathrm{B}}_{6}$ by point-contact Andreev reflection spectroscopy with a Nb probe tip. Below the superconducting transition of Nb, the spectra exhibited a narrow dip at around zero bias superposed on a broad asymmetric background ca…

[Phys. Rev. B 108, 195130] Published Wed Nov 15, 2023

Analytic density of states of a tight-binding model for a two-dimensional Chern insulator
Vera Uzunova and Krzysztof Byczuk
Author(s): Vera Uzunova and Krzysztof Byczuk

We present analytic expressions for the density of states and its consistent derivation for the two-dimensional Qi-Wu-Zhang (QWZ) Hamiltonian—a generic model for the Chern topological insulators of class A. This density of states is expressed in terms of elliptical integrals. We discuss and plot spe…

[Phys. Rev. B 108, 195131] Published Wed Nov 15, 2023

Exciton spectra and layer decomposition in ${\mathrm{MoSi}}_{2}{\mathrm{N}}_{4}/{\mathrm{WSi}}_{2}{\mathrm{N}}_{4}$ heterostructures
Hongxia Zhong, Shiyuan Gao, Guangyong Zhang, Zhengyu Xu, Jianmeng Zhou, Xingbing Li, Cheng Lu, and Yunhua Wang
Author(s): Hongxia Zhong, Shiyuan Gao, Guangyong Zhang, Zhengyu Xu, Jianmeng Zhou, Xingbing Li, Cheng Lu, and Yunhua Wang

Excitons in van der Waals heterostructures having interlayer or intralayer types are responsible for their optical absorption properties. Here, we systematically investigate the band alignment and excitons in the ${\mathrm{MoSi}}_{2}{\mathrm{N}}_{4}/{\mathrm{WSi}}_{2}{\mathrm{N}}_{4}$ heterostructur…

[Phys. Rev. B 108, 205131] Published Wed Nov 15, 2023

Magnetic field induced Weyl state in the van der Waals–type antiferromagnet ${\mathrm{GdTe}}_{3}$
Y. M. Wan, E.-J. Cheng, H.-Y. Ma, X. F. Yang, X. F. Hou, X. J. Chen, X. Zhang, C. Y. Xi, Z. C. Zhong, J. P. Liu, Y. F. Guo, and S. Y. Li
Author(s): Y. M. Wan, E.-J. Cheng, H.-Y. Ma, X. F. Yang, X. F. Hou, X. J. Chen, X. Zhang, C. Y. Xi, Z. C. Zhong, J. P. Liu, Y. F. Guo, and S. Y. Li

${\mathrm{GdTe}}_{3}$, a van der Waals–type antiferromagnetic (AFM) metal with high mobility, is gaining a lot of attention for its potential use in high-speed spintronic devices as well as for fundamental physics research. Due to the magnetocrystalline anisotropy of ${\mathrm{GdTe}}_{3}$, exotic ef…

[Phys. Rev. B 108, 205132] Published Wed Nov 15, 2023

Found 3 papers in prl
Date of feed: Thu, 16 Nov 2023 04:17:18 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)

Ab Initio Phase Diagram of Gold in Extreme Conditions
P. Richard, A. Castellano, R. Béjaud, L. Baguet, J. Bouchet, G. Geneste, and F. Bottin
Author(s): P. Richard, A. Castellano, R. Béjaud, L. Baguet, J. Bouchet, G. Geneste, and F. Bottin

A phase diagram of gold is proposed in the [0; 1000] GPa and [0; 10 000] K ranges of pressure and temperature, respectively, topologically modified with respect to previous predictions. Using finite-temperature ab initio simulations and nonequilibirum thermodynamic integration, both accelerated by m…

[Phys. Rev. Lett. 131, 206101] Published Wed Nov 15, 2023

Distinguishing Different Stackings in Layered Materials via Luminescence Spectroscopy
Matteo Zanfrognini, Alexandre Plaud, Ingrid Stenger, Frédéric Fossard, Lorenzo Sponza, Léonard Schué, Fulvio Paleari, Elisa Molinari, Daniele Varsano, Ludger Wirtz, François Ducastelle, Annick Loiseau, and Julien Barjon
Author(s): Matteo Zanfrognini, Alexandre Plaud, Ingrid Stenger, Frédéric Fossard, Lorenzo Sponza, Léonard Schué, Fulvio Paleari, Elisa Molinari, Daniele Varsano, Ludger Wirtz, François Ducastelle, Annick Loiseau, and Julien Barjon

Despite its simple crystal structure, layered boron nitride features a surprisingly complex variety of phonon-assisted luminescence peaks. We present a combined experimental and theoretical study on ultraviolet-light emission in hexagonal and rhombohedral bulk boron nitride crystals. Emission spectr…

[Phys. Rev. Lett. 131, 206902] Published Wed Nov 15, 2023

Experimental Realization of Geometry-Dependent Skin Effect in a Reciprocal Two-Dimensional Lattice
Wei Wang, Mengying Hu, Xulong Wang, Guancong Ma, and Kun Ding
Author(s): Wei Wang, Mengying Hu, Xulong Wang, Guancong Ma, and Kun Ding

Recent studies of non-Hermitian periodic lattices unveiled the non-Hermitian skin effect (NHSE), in which the bulk modes under the periodic boundary conditions (PBC) become skin modes under open boundary conditions. The NHSE is a topological effect owing to the nontrivial spectral winding, and such …

[Phys. Rev. Lett. 131, 207201] Published Wed Nov 15, 2023

Found 1 papers in comm-phys

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)

An atomically tailored chiral magnet with small skyrmions at room temperature
Roland K. Kawakami

Communications Physics, Published online: 14 November 2023; doi:10.1038/s42005-023-01444-1

Magnetic skyrmions are topological excitations that have attracted great attention recently for their potential applications in low power, ultrahigh density memory. A major challenge has been to find materials that meet the dual requirement of small skyrmions stable at room temperature. Here, the authors further both these goals by developing epitaxial FeGe films with excess Fe using atomic layer molecular beam epitaxy far from thermal equilibrium.