Found 57 papers in cond-mat
Date of feed: Tue, 12 Dec 2023 01:30:00 GMT

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Topologically compatible non-Hermitian skin effect. (arXiv:2312.05315v1 [cond-mat.mes-hall])
Rijia Lin, Linhu Li

The bulk-boundary correspondence (BBC) relates in-gap boundary modes to bulk topological invariants. In certain non-Hermitian topological systems, conventional BBC becomes invalid in the presence of the non-Hermitian skin effect (NHSE), which manifests as distinct energy spectra under the periodic and open boundary conditions and massive eigenstate localization at boundaries. In this work, we introduce a scheme to induce NHSE without breaking conventional BBC, dubbed as the topologically compatible NHSE (TC-NHSE). In a general one dimensional two-band model, we unveil two types of TC-NHSE that do not alter topological phase transition points under any circumstance or only in a certain parameter regime, respectively. Extending our model into two dimension, we find that TC-NHSE can be selectively compatible to different sets of Weyl points between different bands of the resultant semimetallic system, turning some of them into bulk Fermi arcs while keeping the rest unchanged. Our work hence helps clarify the intricate interplay between topology and NHSE in non-Hermitian systems, and provides a versatile approach for designing non-Hermitian topological systems where topological properties and NHSE do not interfere each other.

Collision times of multivariate Bessel processes with their Weyl chambers' boundaries and their Hausdorff dimension. (arXiv:2312.05420v1 [math.PR])
Nicole Hufnagel, Sergio Andraus

Multivariate Bessel processes, otherwise known as radial Dunkl processes, are stochastic processes defined in a Weyl chamber that are repelled from the latter's boundary by a singular drift with a strength given by the multiplicity function $k$. It is a well-known fact that when $k$ is sufficiently small, these processes hit the Weyl chamber's boundary almost surely, and it was recently shown by the authors that the collision times for the process of type $A$, also known as the Dyson model (a one-dimensional multiple-particle stochastic system), have a Hausdorff dimension that depends on $k$. In this paper, we use the square of the alternating polynomial, which corresponds to the reflection group of the process, to extend this result to all multivariate Bessel processes of rational type, and we show that the Hausdorff dimension of collision times is a piecewise-linear function of the minimum of $k$, but is independent of the dimension of the space where the process lives. This implies that the Hausdorff dimension is independent of the particle number for processes with a particle system representation.

Quasi-phase-matched up- and down-conversion in periodically poled layered semiconductors. (arXiv:2312.05444v1 [physics.optics])
Chiara Trovatello, Carino Ferrante, Birui Yang, Josip Bajo, Benjamin Braun, Xinyi Xu, Zhi Hao Peng, Philipp K. Jenke, Andrew Ye, Jiwoong Park, Philip Walther, Lee A. Rozema, Cory Dean, Andrea Marini, Giulio Cerullo, P. James Schuck

Nonlinear optics lies at the heart of classical and quantum light generation. The invention of periodic poling revolutionized nonlinear optics and its commercial applications by enabling robust quasi-phase-matching in crystals such as lithium niobate. Here we realize a periodically poled van der Waals semiconductor (3R-MoS$_2$). Due to its exceptional nonlinearity, we achieve macroscopic frequency conversion efficiency over a microscopic thickness of only $\SI{1.2}{\micro m}$, $100\times$ thinner than current systems with similar performances. Due to unique intrinsic cavity effects, the thickness-dependent quasi-phase-matched second harmonic signal surpasses the usual quadratic enhancement by 50\%. Further, we report the broadband generation of photon pairs at telecom wavelengths via quasi-phase-matched spontaneous parametric down-conversion. Periodically poled microscopic crystals may unlock on-chip entangled photon-pair sources for integrated quantum circuitry and sensing.

Chiral symmetry breaking and topological charge of graphene nanoribbons. (arXiv:2312.05487v1 [cond-mat.mes-hall])
Hyun Cheol Lee, S.-R. Eric Yang

We explore the edge properties of rectangular graphene nanoribbons featuring two zigzag edges and two armchair edges. Although the self-consistent Hartree-Fock fields break chiral symmetry, our work demonstrates that graphene nanoribbons maintain their status as short-range entangled symmetry-protected topological insulators. The relevant symmetry involves combined mirror and time-reversal operations. In undoped ribbons displaying edge ferromagnetism, the band gap edge states with a topological charge form on the zigzag edges. An analysis of the anomalous continuity equation elucidates that this topological charge is induced by the gap term. In low-doped zigzag ribbons, where the ground state exhibits edge spin density waves, this topological charge appears as a nearly zero-energy edge mode.

Broken weak and strong spin rotational symmetries and tunable interaction between phonon and the continuum in Cr2Ge2Te6. (arXiv:2312.05533v1 [cond-mat.str-el])
Atul G. Chakkar, Deepu Kumar, Pradeep Kumar

Phase transitions with lowering temperature is a manifestation of decreased entropy and within the Landau theoretical framework these are accompanied by the symmetry breaking. Whenever a symmetry is broken weakly or strongly, it leaves its trail and the same may be captured indirectly using renormalization of the quasi-particle excitations. Cr2Ge2Te6, a quasi-two-dimensional magnetic material, provides a rich playground to probe dynamics of the quasi-particle excitations as well as multiple phase transitions with lowering temperature intimately linked with the lattice and spin degrees of freedom. Here, we report in-depth inelastic light scattering measurements on single crystals of Cr2Ge2Te6 as a function of temperature, from 6 K to 330 K, and polarization. Our measurements reveal the long as well as short range ordering of the spins below Tc (~ 60 K) and T* (~ 180 K), respectively; setting the stage for broken rotational and time reversal symmetry, gauged via the distinct renormalization of the phonon self-energy parameters along with the modes intensity. Our measurements also uncovered an intriguing dependence of the interaction strength between discrete state (phonon here) and the underlying continuum, quantified using the Fano asymmetry parameter, as a function of the scattered light polarization. Our results suggest the possibility of tuning the interaction strength using controlled scattered light and symmetry in this 2D magnet.

Chemical potential of magnetic skyrmion quasiparticles in heavy metal/iron bilayers. (arXiv:2312.05535v1 [cond-mat.mtrl-sci])
Balázs Nagyfalusi, László Udvardi, László Szunyogh, Levente Rózsa

We performed metadynamics Monte Carlo simulations to obtain the free energy as a function of the topological charge in the skyrmion-hosting magnetic model systems (Pt$_{0.95}$Ir$_{0.05}$)/Fe/Pd(111) and Pd/Fe/Ir(111), using a spin model containing parameters based on ab initio calculations. Using the topological charge as collective variable, this method allows for evaluating the temperature dependence of the number of skyrmionic quasiparticles. In addition, from the free-energy cost of increasing and decreasing the topological charge of the system we determined chemical potentials as a function of the temperature. At lower temperature, the chemical potential for creating skyrmions and antiskyrmions from the topologically trivial state is different. This splitting of the chemical potential is particularly pronounced for large external magnetic fields when the system is in a field-polarized phase. We observed a change in the shape of the free-energy curves when skyrmion-skyrmion interactions become more pronounced.

Topological Interfaces of Luttinger Liquids. (arXiv:2312.05566v1 [cond-mat.str-el])
Ananda Roy, Hubert Saleur

Topological interfaces of two-dimensional conformal field theories contain information about symmetries of the theory and exhibit striking spectral and entanglement characteristics. While lattice realizations of these interfaces have been proposed for unitary minimal models, the same has remained elusive for the paradigmatic Luttinger liquid {\it i.e.,} the free, compact boson model. Here, we show that a topological interface of two Luttinger liquids can be realized by coupling special one-dimensional superconductors. The gapless excitations in the latter carry charges that are specific integer multiples of the charge of Cooper-pairs. The aforementioned integers are determined by the windings in the target space of the bosonic fields -- a crucial element required to give rise to nontrivial topological interfaces. The latter occur due to the perfect transmission of certain number of Cooper-pairs across the interface. The topological interfaces arise naturally in Josephson junction arrays with the simplest case being realized by an array of experimentally-demonstrated~$0-\pi$ qubits, capacitors and ordinary Josephson junctions. Signatures of the topological interface are obtained through entanglement entropy computations. In particular, the subleading contribution to the so-called interface entropy is shown to differ from existing field theory predictions. The proposed lattice model provides an experimentally-realizable alternative to spin and anyon chains for the analysis of several conjectured conformal fixed points which have so far eluded ab-initio investigation.

Large nonlinear Hall effect and Berry curvature in KTaO3 based two-dimensional electron gas. (arXiv:2312.05578v1 [cond-mat.mtrl-sci])
Jinfeng Zhai, Mattia Trama, Hao Liu, Zhifei Zhu, Yinyan Zhu, Carmine Antonio Perroni, Roberta Citro, Pan He, Jian Shen

The two-dimensional electron gas (2DEG) at oxide interfaces exhibits various exotic properties stemming from interfacial inversion symmetry breaking. In this work, we report the emergence of large nonlinear Hall effects (NHE) in the LaAlO3/KTaO3(111) interface 2DEG under zero magnetic field. Skew scattering was identified as the dominant origin based on the cubic scaling of nonlinear Hall conductivity with longitudinal conductivity and the threefold symmetry. Moreover, a gate-tunable NHE with pronounced peak and dip was observed and reproduced by our theoretical calculation. These results indicate the presence of Berry curvature hotspots and thus a large Berry curvature triple at the oxide interface. Our theoretical calculations confirm the existence of large Berry curvatures from the avoided crossing of multiple 5d-orbit bands, orders of magnitude larger than that in transition-metal dichalcogenides. NHE offers a new pathway to probe the Berry curvature at oxide interfaces, and facilitates new applications in oxide nonlinear electronics.

Infrared photodetection in graphene-based heterostructures: bolometric and thermoelectric effects at the tunneling barrier. (arXiv:2312.05612v1 [cond-mat.mes-hall])
Dmitry A. Mylnikov, Mikhail A. Kashchenko, Kirill N. Kapralov, Davit A. Ghazaryan, Evgenii E. Vdovin, Sergey V. Morozov, Kostya S. Novoselov, Denis A. Bandurin, Alexander I. Chernov, Dmitry A. Svintsov

Graphene/hBN/graphene tunnel devices offer promise as sensitive mid-infrared photodetectors but the microscopic origin underlying the photoresponse in them remains elusive. In this work, we investigated the photocurrent generation in graphene/hBN/graphene tunnel structures with localized defect states under mid-IR illumination. We demonstrate that the photocurrent in these devices is proportional to the second derivative of the tunnel current with respect to the bias voltage, peaking during tunneling through the hBN impurity level. We revealed that the origin of the photocurrent generation lies in the change of the tunneling probability upon radiation-induced electron heating in graphene layers, in agreement with the theoretical model that we developed. Finally, we show that at a finite bias voltage, the photocurrent is proportional to the either of the graphene layers heating under the illumination, while at zero bias, it is proportional to the heating difference. Thus, the photocurrent in such devices can be used for accurate measurements of the electronic temperature providing a convenient alternative to Johnson noise thermometry.

Pressure induced Topological Dirac semimetals in XCdP(X=Na, K). (arXiv:2312.05636v1 [cond-mat.mtrl-sci])
Shivendra Kumar Gupta, Nikhilesh Singh, Saurabh Kumar Sen, Poorva Singh

We present a theoretical investigation on the pressure-induced emergence of Dirac semimetallic properties in the XCdP (X = Na, K) materials, employing first-principles calculations. Dirac semimetals, characterized by linear dispersion relations in their electronic band structures, have gained prominence due to their unique topological features and potential applications in electronic devices. Through systematic calculations, we explore the electronic structure evolution of NaCdP and KCdP under varying pressure conditions. Our findings reveal a compelling transition to a Dirac semimetallic state in both NaCdP and KCdP under applied pressure. The electronic band structures exhibit distinct Dirac cones at the Fermi level, indicating the presence of massless Dirac fermions. Moreover, the pressure-induced Dirac semi-metallic phase in these compounds are found to be robust, and are protected by crystal symmetry. We provide a comprehensive analysis of the bandgap, Fermi surface, and other relevant electronic properties, offering insights into the pressure-driven phase transition in NaCdP and KCdP. The tunability of these materials under external pressure suggests their potential utility in next-generation electronic devices and quantum technologies.

Plasmonic skyrmion quantum thermodynamics. (arXiv:2312.05656v1 [quant-ph])
Vipin Vijayan, L. Chotorlishvili, A. Ernst, M. I. Katsnelson, S. S. P. Parkin, S. K. Mishra

The primary obstacle in the field of quantum thermodynamics revolves around the development and practical implementation of quantum heat engines operating at the nanoscale. One of the key challenges associated with quantum working bodies is the occurrence of "quantum friction," which refers to irreversible wasted work resulting from quantum inter-level transitions. Consequently, the construction of a reversible quantum cycle necessitates the utilization of adiabatic shortcuts. However, the experimental realization of such shortcuts for realistic quantum substances is exceedingly complex and often unattainable. In this study, we propose a quantum heat engine that capitalizes on the plasmonic skyrmion lattice. Through rigorous analysis, we demonstrate that the quantum skyrmion substance, owing to its topological protection, exhibits zero irreversible work. Consequently, our engine operates without the need for adiabatic shortcuts. We checked by numerical calculations and observed that when the system is in the quantum skyrmion phase, the propagated states differ from the initial states only by the geometricl and dynamical phases. The adiabacit evoluation leads to the zero transition matrix elements and zero irreversible work. By employing plasmonic mods and an electric field, we drive the quantum cycle. The fundamental building blocks for constructing the quantum working body are individual skyrmions within the plasmonic lattice. As a result, one can precisely control the output power of the engine and the thermodynamic work accomplished by manipulating the number of quantum skyrmions present.

Topological conditions for impurity effects in graphene nanosystems. (arXiv:2312.05812v1 [cond-mat.mes-hall])
Y.G. Pogorelov, V.M. Loktev

We consider electronic spectra of graphene nanotubes and their perturbation by impurity atoms absorbed at different positions on nanotube surfaces, within the framework of Anderson hybrid model. A special attention is given to the cases when Dirac-like 1D modes appear in the nanotube spectrum and their hybridization with localized impurity states produces, at growing impurity concentration $c$, onset of a mobility gap near the impurity level and even opening, at yet higher $c$, of some narrow delocalized range within this mobility gap. Such behaviors are compared with the similar effects in the previously studied 2D graphene and armchair type graphene nanoribbons. Some possible practical applications are discussed.

Third order nonlinear transport properties in topological chiral antiferromagnetic semimetal CoNb3S6. (arXiv:2312.05824v1 [cond-mat.mtrl-sci])
Junjian Mi, Jialin Li, Miaocong Li, Sheng Xu, Shuang Yu, Zheng Li, Xinyi Fan, Huanfeng Zhu, Qian Tao, Linjun Li, Zhuan Xu

The topology between Bloch states in reciprocal space has attracted tremendous attention in recent years. The quantum geometry of the band structure is composed of quantum metric as real part and berry curvature as imaginary part. While the Berry curvature, the Berry curvature dipole and Berry connection polarizability have been recently revealed by the first order anomalous hall, second order and third order nonlinear Hall effect respectively, the quantum metric induced second order nonlinear transverse and longitudinal response in topological antiferromagnetic material MnBi2Te4 was only very recently reported. Here we demonstrate the similar third order nonlinear transport properties in the topological antiferromagnetic CoNb3S6. We observed that the third order nonlinear longitudinal V3{\omega} xx increase significantly at the antiferromagnetic transition temperature TN ~ 29 K, which was probably induced by the quantum metric without time-reversal symmetry or inversion symmetry. Besides, temperature-dependent nonlinear behaviour was observed in the first order I-V curve below the Neel temperature TN, which was not reported in MnBi2Te4 and FeSn. Such nonlinear I-V behaviour hints for the possible existence of Charge Density Wave (CDW) state, which has been discovered in its sister material FeNb3S6. Simultaneously, two plateaus in the third order nonlinear longitudinal V3{\omega} xx~ I^{\omega} curve are observed, which is also speculated to be related with the possible CDW state. However, the genuine mechanism for the first order nonlinear I-V and its relation with the third order nonlinear transport call for more experimental investigations and theoretical interpretation. Our work provides a way to explore third harmonic nonlinear transport and interaction with magnetic order and CDW.

Imaging the Ettingshausen effect and cryogenic thermoelectric cooling in a van der Waals semimetal. (arXiv:2312.05850v1 [cond-mat.mes-hall])
T. Völkl, A. Aharon-Steinberg, T. Holder, E. Alpern, N. Banu, A. K. Pariari, Y. Myasoedov, M. E. Huber, M. Hücker, E. Zeldov

Attaining viable thermoelectric cooling at cryogenic temperatures is of major fundamental and technological interest for novel electronics and quantum materials applications. In-device temperature control can provide a more efficient and precise thermal environment management as compared to the conventional global cooling. Here we develop nanoscale cryogenic imaging of a magneto-thermoelectric effect and demonstrate absolute cooling and an ultrahigh Ettingshausen effect in exfoliated WTe2 Weyl semimetal flakes at liquid He temperatures. Application of a current and perpendicular magnetic field gives rise to cooling via generation of electron-hole pairs on one side of the sample and heating by their recombination at the opposite side. In contrast to bulk materials, the cooling process is found to be nonmonotonic in magnetic field and device size. The derived model of magneto-thermoelectricity in mesoscopic semimetal devices shows that the cooling efficiency and the induced temperature profiles are governed by the interplay between sample geometry, electron-hole recombination length, magnetic field, and flake and substrate heat conductivities. The findings open the way for direct integration of microscopic thermoelectric cooling and for temperature landscape engineering in novel van der Waals devices.

Thermoelectric Properties of Armchair Graphene Nanoribbons with Array Characteristics. (arXiv:2312.05874v1 [cond-mat.mes-hall])
David M T Kuo

The thermoelectric properties of armchair graphene nanoribbons (AGNRs) with array characteristics are investigated theoretically using the tight-binding model and Green's function technique. The AGNR structures with array characteristics are created by embedding a narrow boron nitride nanoribbon (BNNR) into a wider AGNR, resulting in two narrow AGNRs. This system is denoted as w-AGNR/n-BNNR, where 'w' and 'n' represent the widths of the wider AGNR and narrow BNNR, respectively. We elucidate the coupling effect between two narrow symmetrical AGNRs on the electronic structure of w-AGNR/n-BNNR. A notable discovery is that the power factor of the 15-AGNR/5-BNNR with the minimum width surpasses the quantum limitation of power factor for 1D ideal systems. The energy level degeneracy observed in the first subbands of w-AGNR/n-BNNR structures proves to be highly advantageous in enhancing the electrical power outputs of graphene nanoribbon devices.

Universal patterns of skyrmion magnetizations unveiled by defect implantation. (arXiv:2312.05903v1 [cond-mat.mtrl-sci])
Imara Lima Fernandes, Samir Lounis

Skyrmions are spin-swirling textures hosting wonderful properties with potential implications in information technology. Such magnetic particles carry a magnetization, whose amplitude is crucial to establish them as robust magnetic bits, while their topological nature gives rise to a plethora of exquisite features such as topological protection, the skyrmion and topological Hall effects as well as the topological orbital moment. These effects are all induced by an emergent magnetic field directly proportional to the three-spin scalar chirality, $\chi= (\mathbf{S}_i\times\mathbf{S}_j)\cdot \mathbf{S}_k$, and shaped by the peculiar spatial dependence of the magnetization. Here, we demonstrate the existence of novel chiral magnetizations emerging from the interplay of spin-orbit interaction and either $\chi$ or the two-spin vector chirality $\boldsymbol{\kappa} = \mathbf{S}_i\times\mathbf{S}_j$. By scrutinizing correlations among the spin, orbital (trivial and chiral) magnetizations, we unveil from ab-initio universal patterns, quantify the rich set of magnetizations carried by single skyrmions generated in PdFe bilayer on Ir(111) surface and demonstrate the ability to engineer their magnitude via controlled implantation of impurities. We anticipate that our findings can guide the design of disruptive storage devices based on skyrmionic bits by encoding the desired magnetization with strategic seeding of defects.

Van Hove singularity-induced negative magnetoresistance in Dirac semimetals. (arXiv:2312.05918v1 [cond-mat.mes-hall])
Kai-He Ding, Zhen-Gang Zhu

Negative magnetoresistance (NMR) is a marked feature of Dirac semimetals, and may be caused by multiple mechanisms, such as the chiral anomaly, the Zeeman energy, the quantum interference effect, and the orbital moment. Recently, an experiment on Dirac semimetal Cd$_3$As$_2$ thin films revealed a new NMR feature that depends strongly on the thickness of the sample [T. Schumann, \emph{et al}., Phys. Rev. B 95, 241113(R) (2017)]. Here, we introduce a new mechanism of inducing NMR via the presence of the van Hove singularity (VHS) in the density of states. Theoretical fitting of the experimental data on magnetoconductivity and magnetoresistance shows good agreement, indicating that the observed NMR in thin films of Cd$_3$As$_2$ can be attributed to the VHS. This work provides new insights into the underlying of Dirac semimetals.

Large quantum nonreciprocity in plasmons dragged by drifting electrons. (arXiv:2312.05949v1 [cond-mat.mes-hall])
Debasis Dutta, Amit Agarwal

Collective plasmon modes, riding on top of drifting electrons, acquire a fascinating nonreciprocal dispersion characterized by $\omega_p(\bm{q}) \neq \omega_p(-\bm{q})$. The {\it classical} plasmonic Doppler shift arises from the polarization of the Fermi surface due to the applied DC bias voltage. Going beyond this paradigm, we predict a {\it quantum} plasmonic Doppler shift originating from the quantum metric of the Bloch wavefunction. We systematically compare the classical and quantum Doppler shifts by investigating the drift-induced nonreciprocal plasmon dispersion in generic quantum systems. We demonstrate quantum nonreciprocal plasmons in graphene and twisted bilayer graphene. We show that the quantum plasmonic Doppler shift dominates in \moire systems at large wavevectors, yielding plasmonic nonreciprocity up to 20\% in twisted bilayer graphene. Our findings demonstrate the supremacy of plasmonic quantum Doppler shift in \moire systems, motivating the design of innovative nonreciprocal photonic devices with potential technological implications.

Optomechanical methodology for characterizing the thermal properties of 2D materials. (arXiv:2312.06070v1 [])
Hanqing Liu, Hatem Brahmi, Carla Boix-Constant, Herre S. J. van der Zant, Peter G. Steeneken, Gerard J. Verbiest

Heat transport in two-dimensions is fundamentally different from that in three dimensions. As a consequence, the thermal properties of 2D materials are of great interest, both from scientific and application point of view. However, few techniques are available for accurate determination of these properties in ultrathin suspended membranes. Here, we present an optomechanical methodology for extracting the thermal expansion coefficient, specific heat and thermal conductivity of ultrathin membranes made of 2H-TaS2, FePS3, polycrystalline silicon, MoS2 and WSe2. The obtained thermal properties are in good agreement with values reported in the literature for the same materials. Our work provides an optomechanical method for determining thermal properties of ultrathin suspended membranes, that are difficult to measure otherwise. It can does provide a route towards improving our understanding of heat transport in the 2D limit and facilitates engineering of 2D structures with dedicated thermal performance.

DFT based investigation of structural, elastic, optoelectronic, thermophysical and superconducting state properties of binary Mo3P at different pressures. (arXiv:2312.06073v1 [cond-mat.mtrl-sci])
Md. Sohel Rana, Razu Ahmed, Md. Sajidul Islam, R.S. Islam, S.H. Naqib

In recent years, the investigation of novel materials for various technological applications has gained much importance in materials science research. Tri-molybdenum phosphide (Mo3P), a promising transition metal phosphide (TMP), has gathered significant attention due to its unique structural and electronic properties, which already make it potentially valuable system for catalytic and electronic device applications. Through an in-depth study using the density functional theory (DFT) calculations, this work aims to clarify the basic properties of the Mo3P compound at different pressures. In this work, we have studied the structural, elastic, optoelectronic and thermophysical properties of binary Mo3P compound. In this investigation, we varied uniform hydrostatic pressure from 0 GPa to 30 GPa. A complete geometrical optimization for structural parameters is performed and the obtained values are in good accord with the experimental values where available. It is also found that Mo3P possesses very low level of elastic anisotropy, reasonably good machinability, ductile nature, relatively high Vickers hardness, high Debye temperature and high melting temperature. Thermomechanical properties indicate that the compound has potential to be used as a thermal barrier coating material. The bonding nature in Mo3P has been explored. The electronic band structure shows that Mo3P has no band gap and exhibits conventional metallic behavior. All of the energy dependent optical characteristics demonstrate apparent metallic behavior and agree exactly with the electronic density of states calculations. The compound has excellent reflective and absorptive properties suitable for optical applications. Pressure dependent variations of the physical properties are explored and their possible link with superconductivity has been discussed.

Self-powered programmable van der Waals photodetectors with nonvolatile semi-floating gate. (arXiv:2312.06142v1 [cond-mat.mes-hall])
Fan Liu, Xi Lin, Yuting Yan, Xuetao Gan, Yingchun Cheng, Xiaoguang Luo

Tunable photovoltaic photodetectors are of significant relevance in the fields of programmable and neuromorphic optoelectronics. However, their widespread adoption is hindered by intricate architectural design and energy consumption challenges. This study employs a nonvolatile MoTe2/hBN/graphene semi-floating photodetector to address these issues. Programed with pulsed gate voltage, the MoTe2 channel can be reconfigured from an n+-n to a p-n homojunction, and the photocurrent transition changes from negative to positive values. Scanning photocurrent mapping reveals that the negative and positive photocurrents are attributed to Schottky junction and p-n homojunction, respectively. In the p-n configuration, the device demonstrates self-driven, linear, rapid response (~3 ms), and broadband sensitivity (from 405 to 1500 nm) for photodetection, with typical performances of responsivity at ~0.5 A/W and detectivity ~1.6*10^12 Jones under 635 nm illumination. These outstanding photodetection capabilities emphasize the potential of the semi-floating photodetector as a pioneering approach for advancing logical and nonvolatile optoelectronics.

Approaching the robust linearity in dual-floating van der Waals photodiode. (arXiv:2312.06157v1 [cond-mat.mes-hall])
Jinpeng Xu, Xiaoguang Luo, Xi Lin, Xi Zhang, Fan Liu, Yuting Yan, Siqi Hu, Mingwen Zhang, Nannan Han, Xuetao Gan, Yingchun Cheng, Wei Huang

Two-dimensional (2D) material photodetectors have gained great attention as potential elements for optoelectronic applications. However, the linearity of the photoresponse is often compromised by the carrier interaction, even in 2D photodiodes. In this study, we present a new device concept of dual-floating van der Waals heterostructures (vdWHs) photodiode by employing ambipolar MoTe2 and n-type MoS2 2D semiconductors. The presence of type II heterojunctions on both sides of channel layers effectively deplete carriers and restrict the photocarrier trapping within the channel layers. As a result, the device exhibits robust linear photoresponse under photovoltaic mode from the visible (405 nm) to near-infrared (1600 nm) band. With the built-in electric field of the vdWHs, we achieve a linear dynamic range of ~ 100 dB, responsivity of ~ 1.57 A/W, detectivity of ~ 4.28 * 10^11 Jones, and response speed of ~ 30 {\mu}s. Our results showcase a promising device concept with excellent linearity towards fast and low-loss detection, high-resolution imaging, and logic optoelectronics.

Universality of Anderson Localization Transitions in the Integer and Fractional Quantum Hall Regime. (arXiv:2312.06194v1 [cond-mat.mes-hall])
Simrandeep Kaur, Tanima Chanda, Kazi Rafsanjani Amin, Kenji Watanabe, Takashi Taniguchi, Unmesh Ghorai, Yuval Gefen, G. J. Sreejith, Aveek Bid

Understanding the interplay between electronic interactions and disorder-induced localization has been a longstanding quest in the physics of quantum materials. One of the most convincing demonstrations of the scaling theory of localization for noninteracting electrons has come from plateau transitions in the integer quantum Hall effect with short-range disorder, wherein the localization length diverges as the critical filling factor is approached with a measured scaling exponent close to the theoretical estimates. In this work, we extend this physics to the fractional quantum Hall effect, a paradigmatic phenomenon arising from a confluence of interaction, disorder, and topology. We employ high-mobility trilayer graphene devices where the transport is dominated by short-range impurity scattering, and the extent of Landau level mixing can be varied by a perpendicular electric field. Our principal finding is that the plateau-to-plateau transitions from N+1/3 to N+2/5 and from N+2/5 to N+3/7 fractional states are governed by a universal scaling exponent, which is identical to that for the integer plateau transitions and is independent of the perpendicular electric field. These observations and the values of the critical filling factors are consistent with a description in terms of Anderson localization-delocalization transitions of weakly interacting electron-flux bound states called composite Fermions. This points to a universal effective physics underlying fractional and integer plateau-to-plateau transitions independent of the quasiparticle statistics of the phases and unaffected by weak Landau level mixing. Besides clarifying the conditions for the realization of the scaling regime for composite fermions, the work opens the possibility of exploring a wide variety of plateau transitions realized in graphene, including the fractional anomalous Hall phases and non-abelian FQH states.

Giant ferroelectric polarization in ZrO2 thin film enhanced by an AFE-to-FE phase transition. (arXiv:2312.06216v1 [cond-mat.mtrl-sci])
Xianglong Li, Zengxu Xu, Songbai Hu, Mingqiang Gu, Yuanmin Zhu, Qi Liu, Yihao Yang, Mao Ye, Lang Chen

Ferroelectric fluorite oxides like hafnium (HfO2)-based materials are considered to be one of the most potential candidates for nowadays large-scale integrated-circuits owing to their high compatibility with silicon-based technology. While zirconia (ZrO2)-based fluorites materials, which holds the same fluorite structure, is usually thought to be anti- or week ferroelectric. Our study demonstrates a giant ferroelectric remanent polarization (Pr) amounted to 53 uC/cm2 in orthorhombic ZrO2 growing on (110) SrTiO3, which is comparable to those most outstanding HfO2-based materials. We believe this giant remanent polarization stems from the irreversible anti-ferroelectric-to-ferroelectric (AFE-to-FE) phase transition activated by electric field, which converts the as-grown anti-ferroelectric-ferroelectric blends into purely ferroelectric ZrO2. Our study reverses the poor ferroelectric opinion on ZrO2 by promoting the Pr to the best HfO2-based materials level.

Electrically Tunable Fine Structure of Negatively Charged Excitons in Gated Bilayer Graphene Quantum Dots. (arXiv:2312.06264v1 [cond-mat.mes-hall])
Katarzyna Sadecka, Yasser Saleem, Daniel Miravet, Matthew Albert, Marek Korkusinski, Gabriel Bester, Pawel Hawrylak

We predict here the fine structure of an electrically tunable negatively charged exciton (trion) composed of two electrons and a hole confined in a gated bilayer graphene quantum dot (QD). We start with an atomistic approach, allowing us to compute confined electron and confined hole QD states for a structure containing over one million atoms. Using atomistic wavefunctions we compute Coulomb matrix elements and self-energies. In the next step, by solving the Bethe-Salpeter-like equation for trions, we describe a negatively charged exciton, built as a strongly interacting interlayer complex of two electrons in the conduction band and one hole in the valence band. Unlike in conventional semiconducting QDs, we show that the trion contains a fine structure composed of ten states arising from the valley and spin degrees of freedom. Finally, we obtain absorption into and emission from the trion states. We predict the existence of bright low-energy states and propose to extract the fine structure of the trion using the temperature dependence of emission spectra.

Edge-State-Mediated RKKY Coupling in Graphene Nanoflakes. (arXiv:2312.06277v1 [cond-mat.mes-hall])
Ahmet Utku Canbolat, Ozgur Cakir

We investigate the long-range behavior and size dependence of the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction in hexagonal and triangular graphene nanoflakes with zigzag and arm-chair edges. We employ the tight-binding model with exact diagonalization to calculate the RKKY interaction as a function of the distance between magnetic impurities, nanoflake size, and edge geometry. Our findings demonstrate a strong dependency of the RKKY interaction on edge geometry and flake size, with notable changes in the RKKY interaction strength. We further analyze the influence of structural defects on the interaction strength of exchange interactions.

Towards a phase diagram of the topologically frustrated XY chain. (arXiv:2312.06291v1 [cond-mat.stat-mech])
Daniel Sacco Shaikh, Alberto Giuseppe Catalano, Fabio Cavaliere, Fabio Franchini, Maura Sassetti, Niccolò Traverso Ziani

Landau theory's implicit assumption that microscopic details cannot affect the system's phases has been challenged only recently in systems such as antiferromagnetic quantum spin chains with periodic boundary conditions, where topological frustration can be induced. In this work, we show that the latter modifies the zero temperature phase diagram of the XY chain in a transverse magnetic field by inducing new quantum phase transitions. In doing so, we come across the first case of second order boundary quantum phase transition characterized by a quartic dispersion relation. Our analytical results are supported by numerical investigations and lay the foundation for understanding the phase diagram of this frustrated model.

Inelastic Light Scattering in the Vicinity of a Single-Atom Quantum Point Contact in a Plasmonic Picocavity. (arXiv:2312.06339v1 [cond-mat.mes-hall])
Shuyi Liu, Franco P. Bonafe, Heiko Appel, Angel Rubio, Martin Wolf, Takashi Kumagai

Here, using low-temperature optical scanning tunneling microscopy (STM), we investigate inelastic light scattering (ILS) in the vicinity of a single-atom quantum point contact (QPC). A vibration mode localized at the single Ag adatom on the Ag(111) surface is resolved in the ILS spectrum, resulting from tip-enhanced Raman scattering (TERS) by the atomically-confined plasmonic field in the STM junction. Furthermore, we trace how TERS from the single adatom evolves as a function of the gap distance. The exceptional stability of the low-temperature STM allows to examine distinctly different electron transport regimes of the picocavity, namely in the tunneling and quantum point contact (QPC) regimes. This measurement shows that the vibration mode localized at the adatom and its TERS intensity exhibits a sharp change upon the QPC formation, indicating that the atomic-level structure has a crucial impact on the plasmonic properties. To gain microscopic insights into picocavity optomechanics, we scrutinize the structure and plasmonic field in the STM junction using time-dependent density functional theory. The simulations reveal that atomic-scale structural relaxation at the single-atom QPC results in a discrete change of the plasmonic field strength, volume, and distribution as well as the vibration mode localized at the single atom. These findings give a qualitative explanation for the experimental observations. Furthermore, we demonstrate that strong ILS is a characteristic feature of QPC by continuously forming, breaking, and reforming the atomic contact, and how the plasmonic resonance evolves throughout the non-tunneling, tunneling, and QPC regimes.

Many-body effects on the quasiparticle band structure and optical response of single-layer penta-NiN$_2$. (arXiv:2312.06394v1 [cond-mat.mtrl-sci])
Enesio Marinho Jr., Cesar E. P. Villegas, Pedro Venezuela, Alexandre R. Rocha

We present a comprehensive first-principles study on the optoelectronic properties of the single-layer nickel diazenide (penta-NiN$_2$), a recently synthesized Cairo pentagonal 2D semiconductor. We carry out $ab$ $initio$ calculations based on the density-functional theory (DFT) and many-body perturbation theory, within the framework of Green's functions, to describe the quasiparticle properties and analyze the excitonic effects on the optical properties of monolayer penta-NiN$_2$. Our results reveal a quasiparticle band gap of approximately 1 eV within the eigenvalue self-consistent $GW$ approach, corroborating the monolayer penta-NiN$_2$'s potential in optoelectronics. Remarkably, the acoustic phonon-limited carrier mobility for the monolayer penta-NiN$_2$ exhibits an ultra-high hole mobility of $84{\times}10^4$ cm$^2$/V$\cdot$s. Furthermore, our findings indicate that the material's band gap exhibits an anomalous negative dependence on temperature. Despite being a two-dimensional material, monolayer penta-NiN$_2$ presents resonant excitons in its most prominent absorption peak. Therefore, penta-NiN$_2$ boasts compelling and promising properties that merit exploration in optoelectronics and high-speed devices.

Nanoscale strain manipulation of smectic susceptibility in kagome superconductors. (arXiv:2312.06407v1 [cond-mat.supr-con])
Yidi Wang, Hong Li, Siyu Cheng, He Zhao, Brenden R. Ortiz, Andrea Capa Salinas, Stephen D. Wilson, Ziqiang Wang, Ilija Zeljkovic

Exotic quantum solids can host electronic states that spontaneously break rotational symmetry of the electronic structure, such as electronic nematic phases and unidirectional charge density waves (CDWs). When electrons couple to the lattice, uniaxial strain can be used to anchor and control this electronic directionality. Here we reveal an unusual impact of strain on unidirectional "smectic" CDW orders in kagome superconductors AV3Sb5 using spectroscopic-imaging scanning tunneling microscopy. We discover local decoupling between the smectic electronic director axis and the direction of anisotropic strain. While the two are generally aligned along the same direction in regions of small CDW gap, the two become misaligned in regions where CDW gap is the largest. This in turn suggests nanoscale variations in smectic susceptibility, which we attribute to a combination of local strain and electron correlation strength. Overall, we observe an unusually high decoupling rate between the smectic electronic director of the 3-state Potts order and anisotropic strain, revealing weak smecto-elastic coupling in the CDW phase of kagome superconductors. This is phenomenologically different from the extensively studied nemato-elastic coupling in the Ising nematic phase of Fe-based superconductors, providing a contrasting picture of how strain can control electronic unidirectionality in different families of quantum materials.

Micromagnets dramatically enhance effects of viscous hydrodynamic flow in two-dimensional electron fluid. (arXiv:2205.08110v2 [cond-mat.mes-hall] UPDATED)
Jack N. Engdahl, Aydin Cem Keser, Oleg P. Sushkov

The hydrodynamic behavior of electron fluids in a certain range of temperatures and densities is well established in graphene and in 2D semiconductor heterostructures. The hydrodynamic regime is intrinsically based on electron-electron interactions, and therefore it provides a unique opportunity to study electron correlations. Unfortunately, in all existing measurements, the relative contribution of hydrodynamic effects to transport is rather small. Viscous hydrodynamic effects are masked by impurities, interaction with phonons, uncontrolled boundaries and ballistic effects. This essentially limits the accuracy of measurements of electron viscosity. Fundamentally, what causes viscous friction in the electron fluid is the property of the flow called vorticity. In this paper, we propose to use micromagnets to increase the vorticity by orders of magnitude. Experimental realization of this proposal will bring electron hydrodynamics to a qualitatively new precision level, as well as opening a new way to characterize and externally control the electron fluid.

Curvature-induced superconductivity enhancement for ultra-thin superconducting films. (arXiv:2205.14373v3 [cond-mat.mes-hall] UPDATED)
Long Du, Yong-Long Wang, Minsi Li, Jiahong Gu, Lijuan Zhou, Guangzhen Kang, Huiqing Tang, Qinghua Chen

We derive the linearized Ginzburg-Landau (GL) equation for an ultra-thin superconducting film with curvature in a magnetic field. By introducing a novel transverse order parameter that varies slowly along the film, and applying the superconducting/vacuum boundary condition, we decouple the linearized GL equation into a transverse part and a surface part that includes the superconducting geometric potential (GP). The nucleation of the superconducting state in curved thin superconducting films can be equivalently described by the surface part equation. In the equivalent GL free energy of a curved superconducting film, the superconducting GP enables the film to remain in the superconducting state even when the superconducting parameter $ \alpha $ turns positive by further reducing the quadratic term of the order parameter. Furthermore, we numerically investigate the phase transition of a rectangle thin superconducting film bent around a cylindrical surface. Our numerical results show that the superconducting GP enhances the superconductivity of the curved film by weakening the effect of the magnetic field, and the increase of the critical temperature, in units of the bulk critical temperature, is equal to the product of the negative superconducting GP and the square of the zero-temperature coherence length, which agrees with our theoretical predictions.

Topological $p_x+ip_y$ inter-valley coherent state in Moir\'e MoTe$_2$/WSe$_2$ heterobilayers. (arXiv:2206.11666v3 [cond-mat.mtrl-sci] UPDATED)
Ying-Ming Xie, Cheng-Ping Zhang, K. T. Law

Recently, a quantum anomalous Hall (QAH) state was observed in AB stacked moir\'e MoTe$_2$/WSe$_2$ heterobilayers at half-filling. More recent layer-resolved magnetic circular dichroism (MCD) measurements revealed that spin-polarized moir\'e bands from both the MoTe$_2$ and the WSe$_2$ layers are involved at the formation of the QAH state. This scenario is not expected by existing theories. In this work, we suggest that the observed QAH state is a new state of matter, namely, a topological $p_x+ip_y$ inter-valley coherent state (TIVC). We point out that the massive Dirac spectrum of the MoTe$_2$ moir\'e bands, together with the Hund's interaction and the Coulomb interactions give rise to this novel QAH state. Through a self-consistent Hartree-Fock analysis, we find a wide range of interaction strengths and displacement fields that the $p_x+ip_y$-pairing phase is energetically favourable. Besides explaining several key features of the experiments, our theory predicts that the order parameter would involve the pairing of electrons and holes with a definite momentum mismatch such that the pairing would generate a new unit cell which is three times the size of the original moir\'e unit cell, due to the order parameter modulations.

Symmetry-Protected Topological Superconductivity in Magnetic Metals. (arXiv:2208.10225v2 [cond-mat.supr-con] UPDATED)
Zhongyi Zhang, Zhenfei Wu, Chen Fang, Fu-chun Zhang, Jiangping Hu, Yuxuan Wang, Shengshan Qin

We show that topological superconductivity can be generally induced in a magnetic metal through the superconducting proximity effect. In this case, the topological superconductivity originates from band degeneracies controlled by crystalline symmetries. We demonstrate this general scheme in a model with a 4-fold band degeneracy protected by the space group P4=nmm. We show that first order or second-order topological superconductivity can be realized in the presence of a ferromagnetic order or an antiferromagnetic order respectively. We derive the corresponding topological invariants and analyze Majorana modes. Our study provides a general method to realize topological superconductivity and help to identify new platforms to generate Majorana zero modes.

Effects of topological and non-topological edge states on information propagation and scrambling in a Floquet spin chain. (arXiv:2210.15302v2 [cond-mat.stat-mech] UPDATED)
Samudra Sur, Diptiman Sen

The action of any local operator on a quantum system propagates through the system carrying the information of the operator. This is usually studied via the out-of-time-order correlator (OTOC). We numerically study the information propagation from one end of a periodically driven spin-1/2 $XY$ chain with open boundary conditions using the Floquet infinite-temperature OTOC. We calculate the OTOC for two different spin operators, $\sigma^x$ and $\sigma^z$. For sinusoidal driving, the model can be shown to host different types of edge states, namely, topological (Majorana) edge states and non-topological edge states. We observe a localization of information at the edge for both $\sigma^z$ and $\sigma^x$ OTOCs whenever edge states are present. In addition, in the case of non-topological edge states, we see oscillations of the OTOC in time near the edge, the oscillation period being inversely proportional to the gap between the Floquet eigenvalues of the edge states. We provide an analytical understanding of these effects due to the edge states. It was known earlier that the OTOC for the spin operator which is local in terms of Jordan-Wigner fermions ($\sigma^z$) shows no signature of information scrambling inside the light cone of propagation, while the OTOC for the spin operator which is non-local in terms of Jordan-Wigner fermions ($\sigma^x$) shows signatures of scrambling. We report a remarkable `unscrambling effect' in the $\sigma^x$ OTOC after reflections from the ends of the system. Finally, we demonstrate that the information propagates into the system mainly via the bulk states with the maximum value of the group velocity, and we show how this velocity is controlled by the driving frequency and amplitude.

Triclinic BiFeO3: A room-temperature multiferroic phase with enhanced magnetism and resistivity. (arXiv:2211.03123v3 [cond-mat.mtrl-sci] UPDATED)
Md Sariful Sheikh, Tushar Kanti Bhowmik, Alo Dutta, Sujoy Saha, Chhatra R. Joshi, T. P. Sinha

The magnetic and transport properties of BiFeO3/La2NiMnO6 (BFO/LNMO) composite have been investigated both experimentally and theoretically. Unlike the normal rhombohedral (R3c) phase, BFO in the composites is crystallized in the triclinic phase (P1). Interestingly, the composites demonstrate a significant enhancement in the magnetization, magnetoelectric coupling and show higher resistivity than that of the regular BFO (R3c). As LNMO has its Curie temperature at 280 K, the room temperature and above room temperature magnetic contribution in the composites is expected to be from the triclinic BFO phase. Experimentally observed enhancement in magnetization is validated using classical Monte Carlo simulation and density functional theory (DFT) calculations. The calculations reveal higher magnetic moments in triclinic BFO as compared to the rhombohedral BFO. Overall, this study reveals triclinic BFO as the promising room temperature multiferroic phase which is helpful to optimize the multiferroicity of BFO and achieve wider applications in future.

Phase-engineering the Andreev band structure of a three-terminal Josephson junction. (arXiv:2302.14535v2 [cond-mat.mes-hall] UPDATED)
M. Coraiola, D. Z. Haxell, D. Sabonis, H. Weisbrich, A. E. Svetogorov, M. Hinderling, S. C. ten Kate, E. Cheah, F. Krizek, R. Schott, W. Wegscheider, J. C. Cuevas, W. Belzig, F. Nichele

In hybrid Josephson junctions with three or more superconducting terminals coupled to a semiconducting region, Andreev bound states may form unconventional energy band structures, or Andreev matter, which are engineered by controlling superconducting phase differences. Here we report tunnelling spectroscopy measurements of three-terminal Josephson junctions realised in an InAs/Al heterostructure. The three terminals are connected to form two loops, enabling independent control over two phase differences and access to a synthetic Andreev band structure in the two-dimensional phase space. Our results demonstrate a phase-controlled Andreev molecule, originating from two discrete Andreev levels that spatially overlap and hybridise. Signatures of hybridisation are observed in the form of avoided crossings in the spectrum and band structure anisotropies in the phase space, all explained by a numerical model. Future extensions of this work could focus on addressing spin-resolved energy levels, ground state fermion parity transitions and Weyl bands in multiterminal geometries.

Evolution from quantum anomalous Hall insulator to heavy-fermion semimetal in magic-angle twisted bilayer graphene. (arXiv:2304.14064v3 [cond-mat.str-el] UPDATED)
Cheng Huang, Xu Zhang, Gaopei Pan, Heqiu Li, Kai Sun, Xi Dai, Ziyang Meng

The ground states of twisted bilayer graphene (TBG) at chiral and flat-band limit with integer fillings are known from exact solutions, while their dynamical and thermodynamical properties are revealed by unbiased quantum Monte Carlo (QMC) simulations. However, to elucidate experimental observations of correlated metallic, insulating and superconducting states and their transitions, investigations on realistic, or non-chiral cases are vital. Here we employ momentum-space QMC method to investigate the evolution of correlated states in magic-angle TBG away from chiral limit at charge neutrality with polarized spin/valley, which approximates to an experimental case with filling factor $\nu=-3$. We find that the ground state evolves from quantum anomalous Hall insulator into an intriguing correlated semi-metallic state possessing heavy-fermion features as AA hopping strength reaches experimental values. Such a state resembles the recently proposed heavy-fermion representations with localized electrons residing at AA stacking regions and delocalized electrons itinerating via AB/BA stacking regions. The spectral signatures of the localized and itinerant electrons in the heavy-fermion semimetal phase are revealed, with the connection to experimental results being discussed.

Low-dimensional quantum gases in curved geometries. (arXiv:2305.05584v3 [cond-mat.quant-gas] UPDATED)
A. Tononi, L. Salasnich

Atomic gases confined in curved geometries are characterized by distinctive features that are absent in their flat counterparts, such as periodic boundaries, local curvature, and nontrivial topologies. The recent experiments with shell-shaped quantum gases and the study of ring-shaped superfluids point out that the manifold of a quantum gas could soon become a controllable feature, thus allowing to address the fundamental study of curved many-body quantum systems. Here, we review the main geometries realized in the experiments, analyzing the theoretical and experimental status on their phase transitions and on the superfluid dynamics. In perspective, we delineate the study of vortices, the few-body physics, and the search for analog models in various curved geometries as the most promising research areas.

Tuning electronic properties in transition metal dichalcogenides MX$_2$ (M= Mo/W, X= S/Se) heterobilayers with strain and twist angle. (arXiv:2305.09223v3 [cond-mat.mtrl-sci] UPDATED)
Ravina Beniwal, M. Suman Kalyan, Nicolas Leconte, Jeil Jung, Bala Murali Krishna Mariserla, S. Appalakondaiah

We explore the direct to indirect band gap transitions in MX$_2$ (M= Mo/W, X= S/Se) transition metal dichalcogenides heterobilayers for different system compositions, strains, and twist angles based on first principles density functional theory calculations within the G$_0$W$_0$ approximation. The obtained band gaps that typically range between 1.4$-$2.0 eV are direct/indirect for different/same chalcogen atom systems and can often be induced through expansive/compressive biaxial strains of a few percent. A direct to indirect gap transition is verified for heterobilayers upon application of a finite 16$^{\circ}$ twist that weakens interlayer coupling. The large inter-layer exciton binding energies of the order of $\sim$~250~meV estimated by solving the Bethe-Salpeter equation suggest these systems are amenable to be studied through infrared and Raman spectroscopy.

Effect of vacancies on magnetic correlations and conductance in graphene nanoflakes with realistic Coulomb interaction. (arXiv:2305.11085v2 [cond-mat.str-el] UPDATED)
V. S. Protsenko, A. A. Katanin

We study the effect of various configurations of vacancies on the magnetic properties of graphene nanoflake (GNF) with screened realistic long-range electron interaction [T. O. Wehling, et. al., Phys. Rev. Lett. 106, 236805 (2011)] within the functional renormalization group approach. In agreement with previous studies, the presence of vacancies in GNF yields to a strong enhancement of spin-density-wave (SDW) correlations. We show however that only some part of the considered configurations of vacancies posses SDW ground state. The probability of a system with a random configuration of vacancies to be in the SDW ground state increases with increase of vacancy concentration. The disorder-averaged sublattice magnetization increases linearly with the concentration of vacancies. The ratio of the sublattice magnetizations at the center and edges of GNF, averaged over various realizations of disorder, depends only weakly on the number of vacancies. The effects of vacancies on the linear conductance and charge properties of GNF are discussed.

Magnetic exchange interactions at the proximity of a superconductor. (arXiv:2306.02906v2 [cond-mat.supr-con] UPDATED)
Uriel Allan Aceves Rodríguez, Filipe Souza Mendes Guimarães, Sascha Brinker, Samir Lounis

Interfacing magnetism with superconductivity gives rise to a wonderful playground for intertwining key degrees of freedom: Cooper pairs, spin, charge, and spin-orbit interaction, from which emerge a wealth of exciting phenomena, fundamental in the nascent field of superconducting spinorbitronics and topological quantum technologies. Magnetic exchange interactions (MEI), being isotropic or chiral such as the Dzyaloshinskii-Moriya interactions (DMI), are vital in establishing the magnetic behavior at these interfaces as well as in dictating not only complex transport phenomena, but also the manifestation of topologically trivial or non-trivial objects as skyrmions, spirals, Yu-Shiba-Rusinov states and Majorana modes. Here, we propose a methodology enabling the extraction of the tensor of MEI from electronic structure simulations accounting for superconductivity. We apply our scheme to the case of a Mn layer deposited on Nb(110) surface and explore proximity-induced impact on the MEI. Tuning the superconducting order parameter, we unveil potential change of the magnetic order accompanied with chirality switching. Owing to its simple formulation, our methodology can be readily implemented in state-of-the-art frameworks capable of tackling superconductivity and magnetism. Our findings opens intriguing exploration paths, where chirality and magnetism can be engineered depending on the conducting nature of magneto-superconducting interfaces. We thus foresee implications in the simulations and prediction of topological superconducting bits as well as in cryogenic superconducting hybrid devices involving magnetic units.

Lifshitz transitions and angular conductivity diagrams in metals with complex Fermi surfaces. (arXiv:2306.12225v3 [cond-mat.mtrl-sci] UPDATED)
A. Ya. Maltsev

We consider the Lifshitz topological transitions and the corresponding changes in the galvanomagnetic properties of a metal from the point of view of the general classification of open electron trajectories arising on Fermi surfaces of arbitrary complexity in the presence of magnetic field. The construction of such a classification is the content of the Novikov problem and is based on the division of non-closed electron trajectories into topologically regular and chaotic trajectories. The description of stable topologically regular trajectories gives a basis for a complete classification of non-closed trajectories on arbitrary Fermi surfaces and is connected with special topological structures on these surfaces. Using this description, we describe here the distinctive features of possible changes in the picture of electron trajectories during the Lifshitz transitions, as well as changes in the conductivity behavior in the presence of a strong magnetic field. As it turns out, the use of such an approach makes it possible to describe not only the changes associated with stable electron trajectories, but also the most general changes of the conductivity diagram in strong magnetic fields.

Laughlin's quasielectron as a non-local composite fermion. (arXiv:2306.13972v2 [cond-mat.str-el] UPDATED)
Alberto Nardin, Leonardo Mazza

We discuss the link between the quasielectron wavefunctions proposed by Laughlin and by Jain and show both analytically and numerically that Laughlin's quasielectron is a non-local composite fermion state. Composite-fermion states are typically discussed in terms of the composite-fermion Landau levels (also known as Lambda levels). In standard composite-fermion quasielectron wavefunctions the excited Lambda levels have sub-extensive occupation numbers. However, once the Laughlin's quasielectron is reformulated as a composite fermion, an overall logarithmic occupation of the first Lambda level is made apparent, which includes orbitals that are localized at the boundary of the droplet. Even though the wavefunction proposed by Laughlin features a localised quasielectron with well-defined fractional charge, it exhibits some non-trivial boundary properties which motivate our interpretation of Laughlin's quasielectron as a non-local object. This has an important physical consequence: Laughlin's quasielectron fractionalizes an incorrect spin, deeply related to the anyonic braiding statistics. We conclude that Laughlin's quasielectron is not a good candidate for a quasielectron wavefunction.

Nontrivial worldline winding in non-Hermitian quantum systems. (arXiv:2307.01260v2 [quant-ph] UPDATED)
Shi-Xin Hu, Yongxu Fu, Yi Zhang

Amid the growing interest in non-Hermitian quantum systems, non-interacting models have received the most attention. Here, through the stochastic series expansion quantum Monte Carlo method, we investigate non-Hermitian physics in interacting quantum systems, e.g., various non-Hermitian quantum spin chains. While calculations yield consistent numerical results under open boundary conditions, non-Hermitian quantum systems under periodic boundary conditions observe an unusual concentration of imaginary-time worldlines over nontrivial winding and require enhanced ergodicity between winding-number sectors for proper convergences. Such nontrivial worldline winding is an emergent physical phenomenon that also exists in other non-Hermitian models and analytical approaches. Alongside the non-Hermitian skin effect and the point-gap spectroscopy, it largely extends the identification and analysis of non-Hermitian topological phenomena to quantum systems with interactions, finite temperatures, biorthogonal basis, and periodic boundary conditions in a novel and controlled fashion. Finally, we study the direct physical implications of such nontrivial worldline winding, which bring additional, potentially quasi-long-range contributions to the entanglement entropy.

Correlated insulator in two Coulomb-coupled quantum wires. (arXiv:2307.13688v2 [cond-mat.str-el] UPDATED)
Yang-Zhi Chou, Sankar Das Sarma

Motivated by the recently discovered incompressible insulating phase in the bilayer graphene exciton experiment [arXiv:2306.16995], we study using bosonization two Coulomb-coupled spinless quantum wires and examine the possibility of realizing the similar phenomenology in one dimension. We explore the possible phases as functions of $k_{F}$'s and interactions. We show that an incompressible insulating phase can arise for two lightly doped electron-hole quantum wires (i.e., $k_{F1}=-k_{F2}$ and small $|k_{F1}|$) due to strong interwire interactions. Such an insulating phase forms a parity-even wire-antisymmetric charge density wave without interwire phase coherence, which melts to a phase allowing for a perfect negative drag upon heating. The finite-temperature response is qualitatively consistent with the ``exciton solid'' phenomenology in the bilayer graphene exciton experiment.

Fusion mechanism for quasiparticles and topological quantum order in the lowest Landau level. (arXiv:2308.03548v2 [cond-mat.str-el] UPDATED)
Arkadiusz Bochniak, Gerardo Ortiz

Starting from Halperin multilayer systems we develop a hierarchical scheme that generates, bosonic and fermionic, single-layer quantum Hall states (or vacua) of arbitrary filling factor. Our scheme allows for the insertion of quasiparticle excitations with either Abelian or non-Abelian statistics and quantum numbers that depend on the nature of the original vacuum. Most importantly, it reveals a fusion mechanism for quasielectrons and magnetoexcitons that generalizes ideas about particle fractionalization introduced in A. Bochniak, Z. Nussinov, A. Seidel, and G. Ortiz, Commun. Phys. 5, 171 (2022) for the case of Laughlin fluids. In addition, in the second quantization representation, we uncover the inherent topological quantum order characterizing these vacua. In particular, we illustrate the methodology by constructing generalized composite (generalized Read) operators for the non-Abelian Pfaffian and Hafnian quantum fluid states.

Klein-bottle quadrupole insulators and Dirac semimetals. (arXiv:2309.07784v4 [cond-mat.mes-hall] UPDATED)
Chang-An Li, Junsong Sun, Song-Bo Zhang, Huaiming Guo, Björn Trauzettel

The Benalcazar-Bernevig-Hughes (BBH) quadrupole insulator model is a cornerstone model for higher-order topological phases. It requires \pi-flux threading through each plaquette of the two-dimensional Su-Schrieffer-Heeger model. Recent studies showed that particular \pi-flux patterns can modify the fundamental domain of momentum space from the shape of a torus to a Klein bottle with emerging topological phases. By designing different \pi-flux patterns, we propose two types of Klein-bottle BBH models. These models show rich topological phases, including Klein-bottle quadrupole insulators and Dirac semimetals. The phase with nontrivial Klein-bottle topology shows twined edge modes at open boundaries. These edge modes can further support second-order topology, yielding a quadrupole insulator. Remarkably, both models are robust against flux perturbations. Moreover, we show that different \pi-flux patterns dramatically affect the phase diagram of the Klein-bottle BBH models. Going beyond the original BBH model, Dirac semimetal phases emerge in Klein-bottle BBH models featured by the coexistence of twined edge modes and bulk Dirac points.

Percolation-induced PT symmetry breaking. (arXiv:2309.15008v2 [cond-mat.stat-mech] UPDATED)
Mengjie Yang, Ching Hua Lee

We propose a new avenue in which percolation, which has been much associated with critical phase transitions, can also dictate the asymptotic dynamics of non-Hermitian systems by breaking PT symmetry. Central to it is our newly-designed mechanism of topologically guided gain, where chiral edge wavepackets in a topological system experience non-Hermitian gain or loss based on how they are topologically steered. For sufficiently wide topological islands, this leads to irreversible growth due to positive feedback from interlayer tunneling. As such, a percolation transition that merges small topological islands into larger ones also drives the edge spectrum across a real to complex transition. Our discovery showcases intriguing dynamical consequences from the triple interplay of chiral topology, directed gain and interlayer tunneling, and suggests new routes for the topology to be harnessed in the control of feedback systems.

Exciton-Polariton Condensates: A Fourier Neural Operator Approach. (arXiv:2309.15593v2 [cond-mat.quant-gas] UPDATED)
Surya T. Sathujoda, Yuan Wang, Kanishk Gandhi

Advancements in semiconductor fabrication over the past decade have catalyzed extensive research into all-optical devices driven by exciton-polariton condensates. Preliminary validations of such devices, including transistors, have shown encouraging results even under ambient conditions. A significant challenge still remains for large scale application however: the lack of a robust solver that can be used to simulate complex nonlinear systems which require an extended period of time to stabilize. Addressing this need, we propose the application of a machine-learning-based Fourier Neural Operator approach to find the solution to the Gross-Pitaevskii equations coupled with extra exciton rate equations. This work marks the first direct application of Neural Operators to an exciton-polariton condensate system. Our findings show that the proposed method can predict final-state solutions to a high degree of accuracy almost 1000 times faster than CUDA-based GPU solvers. Moreover, this paves the way for potential all-optical chip design workflows by integrating experimental data.

Interacting nodal semimetals with non-linear bands. (arXiv:2310.03653v2 [cond-mat.str-el] UPDATED)
Arianna Poli, Niklas Wagner, Max Fischer, Alessandro Toschi, Giorgio Sangiovanni, Sergio Ciuchi

We investigate the quasi-particle and transport properties of a model describing interacting Dirac and Weyl semimetals in the presence of local Hubbard repulsion $U$, where we explicitly include a deviation from the linearity of the energy-momentum dispersion through an intermediate-energy scale $\Lambda$. Our focus lies on the correlated phase of the semimetal. At the nodal point, the renormalization of spectral weight at a fixed temperature $T$ exhibits a weak dependence on $\Lambda$ but is sensitive to the proximity to the Mott transition. Conversely, the scattering rate of quasi-particles and the resistivity display high-temperature exponents that crucially rely on $\Lambda$, leading to a crossover towards a conventional Fermi-liquid behaviour at finite T. Finally, by employing the Nernst-Einstein relation for conductivity, we identify a corresponding density crossover as a function of the chemical potential.

Large Rashba spin splitting, double SU(2) spin symmetry, and pure Dirac fermion system in PtSe$_2$ nanoribbon. (arXiv:2311.09931v2 [cond-mat.mes-hall] UPDATED)
Bo-Wen Yu, Bang-Gui Liu

Two-dimensional transition metal dichalcogenides host interesting physics and have potential applications in various fields. Recently, it is shown experimentally and theoretically that semiconducting monolayer PtSe$_2$ nanoflakes with neutral zigzag edges are stable. Here, we study PtSe$_2$ nanoribbons with the stable edges through first-principles investigation, and find relativstic electron energy dispersion with large Rashba spin splitting in the low-energy bands (even $N$) which originates from the nanoribbon edges. It is shown that there exists SU(2) spin symmetry in both of the conduction and valence bands, which implies conserved spin transport or persistent spin helix (conserved spin structure) along each edge. When the inter-edge interaction becomes week, a nearly-perfect Dirac fermion system can be achieved for each nanoribbon edge through combining the valence and conduction bands. These electronic systems can realize important effects and could be useful for high-performance spintronic and optoelectronic applications.

Weyl orbits as probe of chiral separation effect in magnetic Weyl semimetals. (arXiv:2311.12712v3 [cond-mat.mes-hall] UPDATED)

We consider magnetic Weyl semimetals. First of all we review relation of intrinsic anomalous Hall conductivity, band contribution to intrinsic magnetic moment, and the conductivity of chiral separation effect (CSE) to the topological invariants written in terms of the Wigner transformed Green functions (with effects of interaction and disorder taken into account). Next, we concentrate on the CSE. The corresponding bulk axial current would result in accumulation of particles and holes of opposite chiralities at the surface of the sample. However, this accumulation is compensated by the flow of the states in momentum space along the Fermi arcs. Together with the bulk CSE current this flow forms closed Weyl orbits. Their detection can be considered as experimental discovery of chiral separation effect. Previously it was proposed to detect Weyl orbits through the observation of quantum oscillations \cite{Potter_2014} . We propose the alternative way to detect existence of Weyl orbits through the observation of their contributions to Hall conductance.

The Conjugate Composite Fermi Liquid. (arXiv:2311.16250v2 [cond-mat.str-el] UPDATED)
Nayan Myerson-Jain, Chao-Ming Jian, Cenke Xu

Recent experimental observations of the fractional quantum anomalous Hall effect in spin/valley polarized moir\'{e} systems call for a more expansive theoretical exploration of strongly correlated physics in partially filled topological bands. In this work we study a state that we refer to as the conjugate-composite Fermi liquid (cCFL), which arises when a pair of Chern bands with opposite Chern numbers are both half-filled. We demonstrate that the cCFL is the parent state of various interesting phenomena. As an example, we demonstrate that with the existence of an inplane spin order, the cCFL could be driven into a quantum bad metal phase, in the sense that it is a metallic phase whose zero temperature longitudinal resistivity is finite, but far greater than the Mott-Ioffe-Regal limit, i.e. $\rho^e_{xx} \gg h/e^2$. The bad metal phase is also accompanied with a new Wiedemann-Franz law, meaning the thermal conductivity is proportional to the electrical resistivity rather than conductivity. Other proximate phases of the cCFL such as superconductivity and a chiral spin liquid phase can occur when the composite fermions (CF) form the inter-valley CF-exciton condensate.

Acoustic lattice instabilities at the magneto-structural transition in Fe$_{1.057(7)}$Te. (arXiv:2311.16853v2 [cond-mat.str-el] UPDATED)
K. Guratinder, E. Chan, E. E. Rodriguez, J. A. Rodriguez-Rivera, U. Stuhr, A. Stunault, R. Travers, M. A. Green, N. Qureshi, C. Stock

Fe$_{1.057(7)}$Te undergoes a first-order tetragonal to monoclinc structural transition at T$_{S} \sim 70$ K, breaking the C$_{4}$ lattice symmetry and simultaneously breaking time reversal symmetry with bicollinear magnetic order. We investigate the soft acoustic lattice dynamics near this combined magneto-structural transition. We apply spherically neutron polarimetry to study the static magnetism near this transition, characterized with x-ray powder diffraction, and find no evidence of static incommensurate magnetic correlations near the onset of monoclinic and bicollinear antiferromagnetic order. This fixes the position of our single crystal sample in the Fe$_{1+x}$Te phase diagram in the magnetic bicollinear region and illustrates that our sample statically undergoes a transition from a paramagnetic phase to a low-temperature bicollinear phase. We then apply neutron spectroscopy to study the acoustic phonons, related to elastic deformations of the lattice. We find a temperature dependent soft acoustic branch for phonons propagating along [010] and polarized along [100]. The slope of this acoustic phonon branch is sensitive to the elastic constant $C_{66}$ and the shear modulus. The temperature dependence of this branch displays a softening with a minimum near the magneto-structural transition of T$_{S}$ $\sim$ 70 K and a recovery within the magnetically ordered low temperature phase. Soft acoustic instabilities are present in the collinear phases of the chalcogenides Fe$_{1+x}$Te where nematic order found in Fe$_{1+\delta}$Se is absent. We speculate, based on localized single-ion magnetism, that the relative energy scale of magnetic spin-orbital coupling on the Fe$^{2+}$ transition metal ion is important for the presence of a nematicity in the chalcogenides.

Hyperdeterminants and Composite fermion States in Fractional Chern Insulators. (arXiv:2312.00636v2 [cond-mat.str-el] UPDATED)
Xiaodong Hu, Di Xiao, Ying Ran

Fractional Chern insulators (FCI) were proposed theoretically about a decade ago. These exotic states of matter are fractional quantum Hall states realized when a nearly flat Chern band is partially filled, even in the absence of an external magnetic field. Recently, exciting experimental signatures of such states have been reported in twisted MoTe$_2$ bilayer systems. Motivated by these experimental and theoretical progresses, in this paper, we develop a projective construction for the composite fermion states (either the Jain's sequence or the composite Fermi liquid) in a partially filled Chern band with Chern number $C=\pm1$, which is capable of capturing the microscopics, e.g., symmetry fractionalization patterns and magnetoroton excitations. On the mean-field level, the ground states' and excitated states' composite fermion wavefunctions are found self-consistently in an enlarged Hilbert space. Beyond the mean-field, these wavefunctions can be projected back to the physical Hilbert space to construct the electronic wavefunctions, allowing direct comparison with FCI states from exact diagonalization on finite lattices. We find that the projected electronic wavefunction corresponds to the \emph{combinatorial hyperdeterminant} of a tensor. When applied to the traditional Galilean invariant Landau level context, the present construction exactly reproduces Jain's composite fermion wavefunctions. We apply this projective construction to the twisted bilayer MoTe$_2$ system. Experimentally relevant properties are computed, such as the magnetoroton band structures and quantum numbers.

Interplay between Haldane and modified Haldane models in $\alpha$-$T_{3}$ lattice: Band structures, phase diagrams and edge states. (arXiv:2312.00642v2 [cond-mat.str-el] UPDATED)
Kok Wai Lee, Pei-Hao Fu, Yee Sin Ang

We study the topological properties of the Haldane and modified Haldane models in $\alpha$-$T_{3}$ lattice. The band structures and phase diagrams of the system are investigated. Individually, each model undergoes a distinct phase transition: (i) the Haldane-only model experiences a topological phase transition from the Chern insulator ($\mathcal{C} = 1$) phase to the higher Chern insulator ($\mathcal{C} = 2$) phase; while (ii) the modified-Haldane-only model experiences a phase transition from the topological metal ($\mathcal{C} = 2$) phase to the higher Chern insulator ($\mathcal{C} = 2$) phase and we show that $\mathcal{C}$ is insufficient to characterize this system because $\mathcal{C}$ remains unchanged before and after the phase transition. By plotting the Chern number and $\mathcal{C}$ phase diagram, we show that in the presence of both Haldane and modified Haldane models in the $\alpha$-$T_{3}$ lattice, the interplay between the two models manifests three distinct topological phases, namely the $\mathcal{C} = 1$ Chern insulator (CI) phase, $\mathcal{C} = 2$ higher Chern insulator (HCI) phase and $\mathcal{C} = 2$ topological metal (TM) phase. These results are further supported by the $\alpha$-$T_{3}$ zigzag edge states calculations. Our work elucidates the rich phase evolution of Haldane and modified Haldane models as $\alpha$ varies continuously from $0$ to $1$ in an $\alpha$-$T_3$ model.

Found 12 papers in prb
Date of feed: Tue, 12 Dec 2023 04:17:04 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)

Spatial inhomogeneity of superconducting gap in epitaxial monolayer ${\mathrm{FeTe}}_{1−x}{\mathrm{Se}}_{x}$ films
Yaowu Liu, Luxin Li, Zheng Xie, Zichun Zhang, Sidan Chen, Lichen Ji, Wei Chen, Xinyu Zhou, Xiaopeng Hu, Xi Chen, Qi-Kun Xue, and Shuai-Hua Ji
Author(s): Yaowu Liu, Luxin Li, Zheng Xie, Zichun Zhang, Sidan Chen, Lichen Ji, Wei Chen, Xinyu Zhou, Xiaopeng Hu, Xi Chen, Qi-Kun Xue, and Shuai-Hua Ji

Monolayer ${\mathrm{FeTe}}_{1−x}{\mathrm{Se}}_{x}$ films grown on a ${\mathrm{SrTiO}}_{3}(001)$ substrate is a promising platform to explore both high-temperature and topological superconductivity. Using molecular beam epitaxy, we successfully synthesized monolayer ${\mathrm{FeTe}}_{1−x}{\mathrm{Se}…

[Phys. Rev. B 108, 214514] Published Mon Dec 11, 2023

Azimuthal orientation guided topological defect evolution across the nematic-smectic phase transition
Jin-Bing Wu, Sai-Bo Wu, and Wei Hu
Author(s): Jin-Bing Wu, Sai-Bo Wu, and Wei Hu

Topological defects are of fundamental interest to wide branches of physics. Exploiting the structural evolutions and behaviors of topological defects across the phase transition is vital in understanding complicated condensed matter. Via presetting different initial azimuthal orientations of a squa…

[Phys. Rev. B 108, 224107] Published Mon Dec 11, 2023

Revealing the origin of the topological Hall effect in the centrosymmetric shape memory Heusler alloy ${\mathrm{Mn}}_{2}\mathrm{NiGa}$: A combined experimental and theoretical investigation
Shivani Rastogi, Nisha Shahi, Vishal Kumar, Gaurav K. Shukla, Satadeep Bhattacharjee, and Sanjay Singh
Author(s): Shivani Rastogi, Nisha Shahi, Vishal Kumar, Gaurav K. Shukla, Satadeep Bhattacharjee, and Sanjay Singh

Skyrmions are localized swirling noncoplanar spin textures offering a promising revolution in future spintronic applications. These topologically nontrivial spin textures lead to an additional contribution to the Hall effect, called the topological Hall effect. Here, we investigate the origin of the…

[Phys. Rev. B 108, 224108] Published Mon Dec 11, 2023

Strain-induced frustrated helimagnetism and topological spin textures in ${\mathrm{LiCrTe}}_{2}$
Weiyi Pan, Xueyang Li, and Junsheng Feng
Author(s): Weiyi Pan, Xueyang Li, and Junsheng Feng

By performing first-principles calculations in conjunction with Monte Carlo simulations, we systematically investigated the frustrated magnetic states induced by in-plane compressive strain in ${\mathrm{LiCrTe}}_{2}$. Our calculations support the idea that the magnetic ground state of the ${\mathrm{…

[Phys. Rev. B 108, 224417] Published Mon Dec 11, 2023

Correlated insulator in two Coulomb-coupled quantum wires
Yang-Zhi Chou and Sankar Das Sarma
Author(s): Yang-Zhi Chou and Sankar Das Sarma

Motivated by the recently discovered incompressible insulating phase in the bilayer graphene exciton experiment [Zeng et al., arXiv:2306.16995], we study using bosonization two Coulomb-coupled spinless quantum wires and examine the possibility of realizing the similar phenomenology in one dimension…

[Phys. Rev. B 108, 235135] Published Mon Dec 11, 2023

Understanding phonon thermal transport in twisted bilayer graphene
Shahid Ahmed, Shadab Alam, and Ankit Jain
Author(s): Shahid Ahmed, Shadab Alam, and Ankit Jain

The phonon thermal transport properties of twisted bilayer graphene are investigated using lattice dynamics and the Boltzmann transport equation. The thermal conductivities of $13.{2}^{∘}$ and $21.{8}^{∘}$ twisted configurations are 56 and 36% lower than the untwisted configuration, which has a room…

[Phys. Rev. B 108, 235202] Published Mon Dec 11, 2023

Rattling vibrations and occupied antibonding states yield intrinsically low thermal conductivity of the Zintl-phase compound KSrBi
Congying Wei, Zhenzhen Feng, Yuli Yan, Gaofeng Zhao, Yuhao Fu, and David J. Singh
Author(s): Congying Wei, Zhenzhen Feng, Yuli Yan, Gaofeng Zhao, Yuhao Fu, and David J. Singh

Zintl-phase compounds garner attention as promising thermoelectric materials due to observations of phonon-glass electron-crystal (PGEC) behavior, in combination with tunability that allows optimization of properties and doping. However, this is very much dependent on the specific materials, and und…

[Phys. Rev. B 108, 235203] Published Mon Dec 11, 2023

Electronic $g$ factor and tunable spin-orbit coupling in a gate-defined InSbAs quantum dot
S. Metti, C. Thomas, and M. J. Manfra
Author(s): S. Metti, C. Thomas, and M. J. Manfra

We investigate transport properties of stable gate-defined quantum dots formed in an ${\mathrm{InSb}}_{0.87}{\mathrm{As}}_{0.13}$ quantum well. High $g$ factor and strong spin-orbit coupling make ${\mathrm{InSb}}_{x}{\mathrm{As}}_{1−x}$ a promising platform for exploration of topological superconduc…

[Phys. Rev. B 108, 235306] Published Mon Dec 11, 2023

Erratum: Maximizing intrinsic anomalous Hall effect by controlling the Fermi level in simple Weyl semimetal films [Phys. Rev. B 105, 201101 (2022)]
Mizuki Ohno, Susumu Minami, Yusuke Nakazawa, Shin Sato, Markus Kriener, Ryotaro Arita, Masashi Kawasaki, and Masaki Uchida
Author(s): Mizuki Ohno, Susumu Minami, Yusuke Nakazawa, Shin Sato, Markus Kriener, Ryotaro Arita, Masashi Kawasaki, and Masaki Uchida
[Phys. Rev. B 108, 239902] Published Mon Dec 11, 2023

Percolation transition in a topological phase
Saikat Mondal, Subrata Pachhal, and Adhip Agarwala
Author(s): Saikat Mondal, Subrata Pachhal, and Adhip Agarwala

Transition out of a topological phase is typically characterized by discontinuous changes in topological invariants along with bulk gap closings. However, as a clean system is geometrically punctured, it is natural to ask the fate of an underlying topological phase. To understand this physics we int…

[Phys. Rev. B 108, L220201] Published Mon Dec 11, 2023

Hybrid dyons, inverted Lorentz force, and magnetic Nernst effect in quantum spin ice
Chris R. Laumann and Roderich Moessner
Author(s): Chris R. Laumann and Roderich Moessner

Topological magnets host two sets of gauge fields: that of native Maxwell electromagnetism, owing to the magnetic dipole moment of its constituent microscopic moments, and that of the emergent gauge theory describing the topological phase. Here, we show that in quantum spin ice, the emergent magneti…

[Phys. Rev. B 108, L220402] Published Mon Dec 11, 2023

Nonlinear planar Hall effect induced by interband transitions: Application to surface states of topological insulators
Jia-Yan Ba, Yi-Min Wang, Hou-Jian Duan, Ming-Xun Deng, and Rui-Qiang Wang
Author(s): Jia-Yan Ba, Yi-Min Wang, Hou-Jian Duan, Ming-Xun Deng, and Rui-Qiang Wang

Motivated by recent experiments observing the nonlinear planar Hall effect (NPHE) in nonmagnetic topological materials, we employ the density matrix method to consider all the intraband and interband transitions. This gives a deeper insight for the different mechanisms of NPHE on the same footing be…

[Phys. Rev. B 108, L241104] Published Mon Dec 11, 2023

Found 2 papers in pr_res
Date of feed: Tue, 12 Dec 2023 04:17:04 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)

Dissipative boundary state preparation
Fan Yang, Paolo Molignini, and Emil J. Bergholtz
Author(s): Fan Yang, Paolo Molignini, and Emil J. Bergholtz

We devise a generic and experimentally accessible recipe to prepare boundary states of topological or nontopological quantum systems through an interplay between coherent Hamiltonian dynamics and local dissipation. Intuitively, our recipe harnesses the spatial structure of boundary states which vani…

[Phys. Rev. Research 5, 043229] Published Mon Dec 11, 2023

Phononic drumhead surface state in the distorted kagome compound RhPb
Andrzej Ptok, William R. Meier, Aksel Kobiałka, Surajit Basak, Małgorzata Sternik, Jan Łażewski, Paweł T. Jochym, Michael A. McGuire, Brian C. Sales, Hu Miao, Przemysław Piekarz, and Andrzej M. Oleś
Author(s): Andrzej Ptok, William R. Meier, Aksel Kobiałka, Surajit Basak, Małgorzata Sternik, Jan Łażewski, Paweł T. Jochym, Michael A. McGuire, Brian C. Sales, Hu Miao, Przemysław Piekarz, and Andrzej M. Oleś

RhPb was initially recognized as one of CoSn-like compounds with $P6/mmm$ symmetry, containing an ideal kagome lattice of $d$-block atoms. However, theoretical calculations predict the realization of the phonon soft mode, which leads to the kagome lattice distortion and stabilization of the structur…

[Phys. Rev. Research 5, 043231] Published Mon Dec 11, 2023

Found 2 papers in nat-comm

Search terms: (topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)|(flatband)|(flat.{1}band)|(LK.{1}99)

Non-identical moiré twins in bilayer graphene
< author missing >

Manipulation of fractionalized charge in the metastable topologically entangled state of a doped Wigner crystal
< author missing >

Found 2 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)

Effects of aberrations on 3D optical topologies
Ebrahim Karimi

Communications Physics, Published online: 09 December 2023; doi:10.1038/s42005-023-01465-w

Optical knots are three-dimensional topologies made of singularities in phase or polarization, but the robustness of their topological structure under optical disturbances is still unexplored. The authors experimentally verify the robustness of optical knots to environmental disturbances, indicating them as a viable vector of information.

Three-dimensional non-Abelian Bloch oscillations and higher-order topological states
Xiangdong Zhang

Communications Physics, Published online: 06 December 2023; doi:10.1038/s42005-023-01474-9

Bloch oscillations (BOs) are developed to be a powerful tool for the detection of topological properties in lattice systems. Here, the authors propose topological BOs in a three-dimensional higher-order topological insulator model and demonstrate the dynamics of the wave-packet and certain higher-order edge states in this model using electronic circuits.