Found 21 papers in cond-mat
Date of feed: Fri, 14 Jul 2023 00:30:00 GMT

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

Emergent dynamics of scale-free interactions in fractional quantum Hall fluids. (arXiv:2307.06361v1 [cond-mat.str-el])
Bo Yang

We show that even in the limit of large cyclotron gap, Landau level (LL) mixing can be dominant with scale-free interaction between charged ``elementary particles" in a fractional quantum Hall system, as long as the filling factor exceeds certain critical values. The corresponding Hamiltonians with scale-free interaction can serve as exact model Hamiltonians for certain composite Fermion or parton states (unlike the well-known TK Hamiltonians where the number of LLs needs to be fixed by hand), and they are natural physical Hamiltonians for 2D systems embedded in higher-dimensional space-time. Even with LL mixing the null spaces of such Hamiltonians (spanned by the ground state and the quasiholes) can be analytically obtained, and we show these are the generalisation of the conformal Hilbert spaces (CHS) to more than one LLs. The effective interaction between the anyons for these topological phases emerges from the kinetic energy of the ``elementary particles", leading to an interesting duality between strongly and weakly interacting systems that can be easily understood via the tuning of parameters in the scale-free interaction. We also propose a novel experimental platform for approximately realising such model Hamiltonians with trion like particles, that can potentially lead to very robust (non-Abelian) FQH phases from two-body Coulomb-based interaction.


Building crystalline topological superconductors from Shiba lattices. (arXiv:2307.06365v1 [cond-mat.mes-hall])
Martina O. Soldini, Felix Küster, Glenn Wagner, Souvik Das, Amal Aldarawsheh, Ronny Thomale, Samir Lounis, Stuart S. P. Parkin, Paolo Sessi, Titus Neupert

Localized or propagating Majorana boundary modes are the key feature of topological superconductors. While being a rarity in natural compounds, the tailored manipulation of quantum matter offers novel opportunities for their realization. Specifically, lattices of Shiba bound states that arise when magnetic adatoms are placed on the surface of a conventional superconductor can be used to create topological minibands within the superconducting gap of the substrate. Here, we exploit the possibilities of scanning tunneling microscopy to create and probe adatom lattices with single atom precision to create topological crystalline superconductors. Their topological character and boundary modes are protected by the spatial symmetries of the adatom lattice. We combine scanning probe spectroscopy, spin-sensitive measurements, first principle calculations, and theoretical modeling to to reveal signatures consistent with the realization of two types of mirror-symmetry protected topological superconductors: (i) with full bulk gap and topological edge as well as higher-order corner states and (ii) with symmetry-protected bulk nodal points. Our results show the immense versatility of Shiba lattices to design the topology and sample geometry of 2D superconductors.


Exciton Confinement in Two-Dimensional, In-Plane, Quantum Heterostructures. (arXiv:2307.06404v1 [cond-mat.mes-hall])
Gwangwoo Kim, Benjamin Huet, Christopher E. Stevens, Kiyoung Jo, Jeng-Yuan Tsai, Saiphaneendra Bachu, Meghan Leger, Kyung Yeol Ma, Nicholas R. Glavin, Hyeon Suk Shin, Nasim Alem, Qimin Yan, Joshua R. Hedrickson, Joan M. Redwing, Deep Jariwala

Two-dimensional (2D) semiconductors are promising candidates for optoelectronic application and quantum information processes due to their inherent out-of-plane 2D confinement. In addition, they offer the possibility of achieving low-dimensional in-plane exciton confinement, similar to zero-dimensional quantum dots, with intriguing optical and electronic properties via strain or composition engineering. However, realizing such laterally confined 2D monolayers and systematically controlling size-dependent optical properties remain significant challenges. Here, we report the observation of lateral confinement of excitons in epitaxially grown in-plane MoSe2 quantum dots (~15-60 nm wide) inside a continuous matrix of WSe2 monolayer film via a sequential epitaxial growth process. Various optical spectroscopy techniques reveal the size-dependent exciton confinement in the MoSe2 monolayer quantum dots with exciton blue shift (12-40 meV) at a low temperature as compared to continuous monolayer MoSe2. Finally, single-photon emission was also observed from the smallest dots at 1.6 K. Our study opens the door to compositionally engineered, tunable, in-plane quantum light sources in 2D semiconductors.


Substrate-Selective Adhesion of Metal Nanoparticles to Graphene Devices. (arXiv:2307.06407v1 [physics.atm-clus])
Patrick J. Edwards, Sean Stuart, James T. Farmer, Ran Shi, Run Long, Oleg V. Prezhdo, Vitaly V. Kresin

Nanostructured electronic devices, such as those based on graphene, are typically grown on top of the insulator SiO2. Their exposure to a flux of small size-selected silver nanoparticles has revealed remarkably selective adhesion: the graphene channel can be made fully metallized while the insulating substrate remains coverage-free. This conspicuous contrast derives from the low binding energy between the metal nanoparticles and a contaminant-free passivated silica surface. In addition to providing physical insight into nanoparticle adhesion, this effect may be of value in applications involving deposition of metallic layers on device working surfaces: it eliminates the need for masking the insulating region and the associated extensive and potentially deleterious pre- and postprocessing.


Dynamics of electronic states in the Intermediate phase of 1T-TaS$_2$. (arXiv:2307.06444v1 [cond-mat.str-el])
Jingwei Dong, Weiyan Qi, Dongbin Shin, Laurent Cario, Zhesheng Chen, Romain Grasset, Davide Boschetto, Mateusz Weis, Pierrick Lample, Ernest Pastor, Tobias Ritschel, Marino Marsi, Amina Taleb, Noejung Park, Angel Rubio, Evangelos Papalazarou, Luca Perfetti

This article reports a comparative study of bulk and surface properties in the transition metal dichalcogenide 1T-TaS$_2$. When heating the sample, the surface displays an intermediate insulating phase that persists for $\sim 10$ K on top of a metallic bulk. The weaker screening of Coulomb repulsion and stiffer Charge Density Wave (CDW) explain such resilience of a correlated insulator in the topmost layers. Both time resolved ARPES and transient reflectivity are employed to investigate the dynamics of electrons and CDW collective motion. It follows that the amplitude mode is always stiffer at the surface and displays variable coupling to the Mott-Peierls band, stronger in the low temperature phase and weaker in the intermediate one.


Interacting Local Topological Markers: A one-particle density matrix approach for characterizing the topology of interacting and disordered states. (arXiv:2307.06447v1 [cond-mat.mes-hall])
Julia D. Hannukainen, Miguel F. Martínez, Jens H. Bardarson, Thomas Klein Kvorning

While topology is a property of a quantum state itself, most existing methods for characterizing the topology of interacting phases of matter require direct knowledge of the underlying Hamiltonian. We offer an alternative by utilizing the one-particle density matrix formalism to extend the concept of the Chern, chiral, and Chern-Simons markers to include interactions. The one-particle density matrix of a free-fermion state is a projector onto the occupied bands, defining a Brillouin zone bundle of the given topological class. This is no longer the case in the interacting limit, but as long as the one-particle density matrix is gapped, its spectrum can be adiabatically flattened, connecting it to a topologically equivalent projector. The corresponding topological markers thus characterize the topology of the interacting phase. Importantly, the one-particle density matrix is defined in terms of a given state alone, making the local markers numerically favorable, and providing an invaluable tool for characterizing topology of interacting systems when only the state itself is available. To demonstrate the practical use of the markers we use the chiral marker to identify the topology of the ground state of the Majorana-XYZ model as well as the midspectrum eigenstates of the Ising-Majorana chain across the transition between the ergodic and many-body localized phases.


Surface-Confined Two-Dimensional Crystal Growth on a Monolayer. (arXiv:2307.06477v1 [cond-mat.mes-hall])
Yanyu Jia, Fang Yuan, Guangming Cheng, Yue Tang, Guo Yu, Tiancheng Song, Pengjie Wang, Ratnadwip Singha, Ayelet July Uzan, Michael Onyszczak, Kenji Watanabe, Takashi Taniguchi, Nan Yao, Leslie M Schoop, Sanfeng Wu

Conventional vapor deposition or epitaxial growth of two-dimensional (2D) materials and heterostructures is conducted in a large chamber in which masses transport from the source to the substrate. Here we report a chamber-free, on-chip approach for growing a 2D crystalline structures directly in a nanoscale surface-confined 2D space. The method is based on a surprising discovery of a rapid, long-distance, non-Fickian transport of a uniform layer of atomically thin palladium (Pd) on a monolayer crystal of tungsten ditelluride (WTe2), at temperatures well below the known melting points of all materials involved. The resulting nanoconfined growth realizes a controlled formation of a stable new 2D crystalline material, Pd7WTe2 , when the monolayer seed is either free-standing or fully encapsulated in a van der Waals stack. The approach is generalizable and highly compatible with nanodevice fabrication, promising to expand the library of 2D materials and their functionalities.


Absence of $3a_0$ Charge Density Wave Order in the Infinite Layer Nickelates. (arXiv:2307.06486v1 [cond-mat.supr-con])
C. T. Parzyck, N. K. Gupta, Y. Wu, V. Anil, L. Bhatt, M. Bouliane, R. Gong, B. Z. Gregory, A. Luo, R. Sutarto, F. He, Y.-D. Chuang, T. Zhou, G. Herranz, L. F. Kourkoutis, A. Singer, D. G. Schlom, D. G. Hawthorn, K. M. Shen

A hallmark of many unconventional superconductors is the presence of many-body interactions which give rise to broken symmetry states intertwined with superconductivity. Recent resonant soft x-ray scattering experiments report commensurate $3a_0$ charge density wave order in the infinite layer nickelates, which has important implications regarding the universal interplay between charge order and superconductivity in both the cuprates and nickelates. Here, we present x-ray scattering and spectroscopy measurements on a series of NdNiO$_{2+x}$ samples which reveal that the signatures of charge density wave order are absent in fully reduced, single-phase NdNiO$_2$. The $3a_0$ superlattice peak instead originates from a partially reduced impurity phase where excess apical oxygens form ordered rows with 3 unit cell periodicity. The absence of any observable charge density wave order in NdNiO$_2$ highlights a crucial difference between the phase diagrams of the cuprate and nickelate superconductors.


Topological Unwinding in an Exciton-Polariton Condensate Array. (arXiv:2307.06550v1 [cond-mat.quant-gas])
Guitao Lyu, Yuki Minami, Na Young Kim, Tim Byrnes, Gentaro Watanabe

The phase distribution in a Bose-Einstein condensate can realize various topological states which can be classified according to distinct winding numbers. While states with different winding numbers are topologically protected in the linear Schr\"odinger equation, when nonlinearities are introduced, violations of the topological protection can occur, leading to unwinding. Exciton-polariton condensates constitute a weakly nonlinear open dissipative system that is well suited to studying such physics. Here we show that exciton-polariton condensates display a spontaneous phase unwinding from a $\pi$- to zero-state. While such an effect was previously observed in a one-dimensional polariton-condensate array and explained as occurring due to single-particle mode competition, we offer a new explanation in terms of collective phase unwinding of metastable states. We clarify that the collective transition is caused by the combined effect of nonlinearity and topological defects in the condensates. Reanalyzing the experimental data, we find an evidence of the collective phase unwinding.


Dynamical freezing and switching in periodically driven bilayer graphene. (arXiv:2307.06589v1 [cond-mat.str-el])
Soumya Sasidharan, Naveen Surendran

A class of integrable models, such as the one-dimensional transverse-field Ising model, respond nonmonotonically to a periodic drive with respect to the driving parameters and freezes almost absolutely for certain combinations of the latter. In this paper, we go beyond the two-band structure of the Ising-like models studied previously and ask whether such unusual nonmonotonic response and near-absolute freezing occur in integrable systems with a higher number of bands. To this end, we consider a tight-binding model for bilayer graphene subjected to an interlayer potential difference. We find that when the potential is driven periodically, the system responds nonmonotonically to variations in the driving amplitude $V_0$ and frequency $\omega$ and shows near absolute freezing for certain values of $V_0/\omega$. However, the freezing occurs only in the presence of a constant bias in the driving, i.e., when $V= V'+V_0 \cos{\omega t}$. When $V'=0$, the freezing is switched off for all values of $V_0/\omega$. We support our numerical results with analytical calculations based on a rotating wave approximation. We also give a proposal to realize the driven bilayer system via ultracold atoms in an optical lattice, where the driving can be implemented by shaking the lattice.


Structural pathway for nucleation and growth of topologically close-packed phase from parent hexagonal crystal. (arXiv:2307.06676v1 [cond-mat.mtrl-sci])
Junyuan Bai, Hongbo Xie, Xueyong Pang, Min Jiang, Gaowu Qin

The solid diffusive phase transformation involving the nucleation and growth of one nucleus is universal and frequently employed but has not yet been fully understood at the atomic level. Here, our first-principles calculations reveal a structural formation pathway of a series of topologically close-packed (TCP) phases within the hexagonally close-packed (hcp) matrix. The results show that the nucleation follows a nonclassical nucleation process, and the whole structural transformation is completely accomplished by the shuffle-based displacements, with a specific 3-layer hcp-ordering as the basic structural transformation unit. The thickening of plate-like TCP phases relies on forming these hcp-orderings at their coherent TCP/matrix interface to nucleate ledge, but the ledge lacks the dislocation characteristics considered in the conventional view. Furthermore, the atomic structure of the critical nucleus for the Mg2Ca and MgZn2 Laves phases was predicted in terms of Classical Nucleation Theory (CNT), and the formation of polytypes and off-stoichiometry in TCP precipitates is found to be related to the nonclassical nucleation behavior. Based on the insights gained, we also employed high-throughput screening to explore several common hcp-metallic (including hcp-Mg, Ti, Zr, and Zn) systems that may undergo hcp-to-TCP phase transformations. These insights can deepen our understanding of solid diffusive transformations at the atomic level, and constitute a foundation for exploring other technologically important solid diffusive transformations.


Manifestation of chiral magnetic current in Floquet-Weyl semimetals. (arXiv:2307.06735v1 [cond-mat.mtrl-sci])
Tsung-Yu Chen, Po-Hao Chou, Chung-Yu Mou

Materials that can host macroscopic persistent current are important because they are useful for energy storage. However, there are very few examples of such materials in nature. Superconductors are known as an example in which flow of supercurrent can persist up to 100,000 years. The chiral magnetic current is possibly the second example predicted by the chiral magnetic effect. It was proposed to be realized in recently discovered Weyl semimetals. However, a no-go theorem negates the chiral magnetic effect and shows that the chiral magnetic current is generally absent in any equilibrium condensed-matter system. Here we show how to break the no-go theorem by resorting to dynamical transitions in time-frequency space. By driving an insulator using a time-periodic potential and coupling it to a phonon heat bath that provides suitable dissipation, we show that a Floquet-Weyl semi-metallic phase with Fermi-Dirac-like distribution emerges. Furthermore, we show that even in the presence of a static magnetic field, the resulting steady Floquet-Weyl semimetal supports non-vanishing chiral magnetic current. Our dynamical model provides a systematic way to fully realize the chiral magnetic effect in condensed matter systems.


Flat bands promoted by Hund's rule coupling in the candidate double-layer high-temperature superconductor La$_3$Ni$_2$O$_7$. (arXiv:2307.06806v1 [cond-mat.supr-con])
Yingying Cao, Yi-feng Yang

We report strongly correlated electronic band structure calculations of the recently discovered double-layer high-temperature superconductor La$_3$Ni$_2$O$_7$ under pressure. Our calculations reveal dual nature of Ni-$d$ electrons with almost localized $d_{z^2}$ orbitals due to onsite Coulomb repulsion and very flat hybridization bands of Ni-$d_{x^2-y^2}$ and Ni-$d_{z^2}$ quasiparticles near the Fermi energy. We find that the quasiparticle effective mass are greatly enhanced by the Hund's rule coupling and their lifetimes are inversely proportional to the temperature, which explains the experimentally observed strange metal behavior in the normal state. We also find strong antiferromagnetic spin correlations of Ni-$d$ electrons, which may provide the pairing force of quasiparticles for the high-temperature superconductivity. These give a potential explanation of two key observations in experiment and connect the superconducting La$_3$Ni$_2$O$_7$ with cuprate high-temperature superconductors. The presence of flat bands and the interplay of orbital-selective Mott, Hund, and Kondo physics make La$_3$Ni$_2$O$_7$ a unique platform for exploring rich emergent quantum many-body phenomena in the future.


Impact of vacancies on twisted bilayer graphene quantum point contacts. (arXiv:2307.06819v1 [cond-mat.mes-hall])
Pablo Moles, Francisco Domínguez-Adame, Leonor Chico

We carry out an extensive numerical study of low-temperature electronic transport in quantum point contacts based on twisted bilayer graphene. Assuming ballistic electron dynamics, quantized plateaus in the conductance are observed in defect-free samples when the twisting angle is large enough. However, plateaus are smeared out and hardly noticeable on decreasing the angle. Close to the magic angle, the conductance around the charge neutrality point drops significantly and the quantization steps visible at higher angles are no longer appreciable. Furthermore, we consider the effects of a random distribution of vacancies on the quantum point contact. Whereas the electron-hole symmetry is broken in pristine samples, we find that this symmetry is restored upon increasing the concentration of vacancies. We explain this effect by a reduction of the effective interlayer coupling due to the presence of the vacancies.


Edge state behavior in a Su-Schrieffer-Heeger like model with periodically modulated hopping. (arXiv:2307.06829v1 [cond-mat.mes-hall])
Satyaki Kar

Su-Schrieffer-Heeger (SSH) model is one of the simplest models to show topological end/edge states and the existence of Majorana fermions. Here we consider a SSH like model both in one and two dimensions where a nearest neighbor hopping features spatially periodic modulations. In the 1D chain, we witness appearance of new in-gap end states apart from a pair of Majorana zero modes (MZM) when the hopping periodicity go beyond two lattice spacings. The pair of MZMs, that appear in the topological regime, characterize the end modes each existing in either end of the chain. These, however, crossover to both-end end modes for small hopping detuning strength in a finite chain. Contrarily in a 2D SSH model with symmetric hopping that we consider, both non-zero and zero energy topological states appear in a finite square lattice even with a simple staggered hopping, though the zero energy modes disappear in a ribbon configuration. Apart from edge modes, the 2D system also features corner modes as well as modes with satellite peaks distributed non-randomly within the lattice. In both the dimensions, an increase in the periodicity of hopping modulation causes the zero energy Majorana modes to become available for either sign of the detuning. But interestingly with different periodicity for hopping modulations in the two directions, the zero energy modes in a 2D model become rarer and does not appear for all strength and sign of the detuning.


Magnon-magnon coupling in synthetic ferrimagnets. (arXiv:2307.06888v1 [cond-mat.mtrl-sci])
A. Sud, K. Yamamoto, K. Z. Suzuki, S. Mizukami, H. Kurebayashi

Magnetic multilayers with interlayer exchange coupling have been widely studied for both static and dynamic regimes. Their dynamical responses depend on the exchange coupling strength and magnetic properties of individual layers. Magnetic resonance spectra in such systems are conveniently discussed in terms of coupling of acoustic and optical modes. At a certain value of applied magnetic field, the two modes come close to being degenerate and the spectral gap indicates the strength of mode hybridisation. In this work, we theoretically and experimentally study the mode hybridisation of interlayer-exchange-coupled moments with dissimilar magnetisation and thickness of two ferromagnetic layers. In agreement with symmetry analysis for eigenmodes, our low-symmetry multilayers exhibit sizable spectral gaps for all experimental conditions. The spectra agree well with the predictions from the Landau-Lifshitz-Gilbert equation at the macrospin limit whose parameters are independently fixed by static measurements.


Second-order Band Topology in Antiferromagnetic (MnBi$_2$Te$_4$)(Bi$_2$Te$_3$)$_{m}$ Films. (arXiv:2307.06903v1 [cond-mat.mtrl-sci])
Fangyang Zhan, Zheng Qin, Dong-Hui Xu, Xiaoyuan Zhou, Da-Shuai Ma, Rui Wang

The existence of fractionally quantized topological corner states serves as a key indicator for two-dimensional second-order topological insulators (SOTIs), yet has not been experimentally observed in realistic materials. Here, based on first-principles calculations and symmetry arguments, we propose a strategy for achieving SOTI phases with in-gap corner states in (MnBi$_2$Te$_4$)(Bi$_2$Te$_3$)$_{m}$ films with antiferromagnetic (AFM) order. Starting from the prototypical AFM MnBi$_2$Te$_4$ bilayer, we show by an effective lattice model that such SOTI phase originate from the interplay between intrinsic spin-orbital coupling and interlayer AFM exchange interactions. Furthermore, we demonstrate that the nontrivial corner states are linked to rotation topological invariants under three-fold rotation symmetry $C_3$, resulting in $C_3$-symmetric SOTIs with corner charges fractionally quantized to $\frac{n}{3} \lvert e \rvert $ (mod $e$). Due to the great recent achievements in (MnBi$_2$Te$_4$)(Bi$_2$Te$_3$)$_{m}$ systems, our results providing reliable material candidates for experimentally accessible AFM higher-order band topology would draw intense attentions.


Higher-order electron-phonon interactions and their effect on the thermal properties of 2D Dirac crystals. (arXiv:2305.18369v2 [cond-mat.mes-hall] UPDATED)
Sina Kazemian, Giovanni Fanchini

To understand the essential properties of Dirac crystals, such as their thermal conductivity, we require models that consider the interaction between Dirac electrons and dispersive acoustic phonons. The exceptionally high thermal conductivity in 2D Dirac crystals is attributed to near-ideal phonon quantum gases, while undesired limitations arise from electron-phonon (e-ph) interactions which have been shown to limit the thermal conductivity up to several microns away. The e-ph thermal conductivity is directly linked to the phonon scattering rate. Conventional calculations overlook phonons with short-dispersive wavelengths, rendering them inadequate for analyzing 2D Dirac crystals. The phonon scattering rate is typically calculated up to the first-order magnitude, considering 3-particle interactions involving the decay of an electron and phonon (EP-E*) to create a new electron. However, processes involving the decay of an electron and the creation of a new electron and phonon (E-E*P*) are neglected. In this study, we present an accurate expression for the phonon scattering rate and e-ph thermal conductivity in 2D Dirac crystals, accounting for short-dispersive wavelength phonons. We demonstrate the significance of the E-E*P* process even at room temperature in calculating the phonon scattering rate and e-ph thermal conductivity, particularly for first-order e-ph interactions. Furthermore, we emphasize the importance of incorporating second-order e-ph interactions, specifically the EP-E*P* interaction involving the decay of an electron and phonon and the creation of a new electron-phonon pair, to accurately determine the phonon scattering rate and e-ph thermal conductivity at high temperatures and low Fermi energies. This 4-particle interaction process plays a crucial role in characterizing these properties effectively.


A no-go result for implementing chiral symmetries by locality-preserving unitaries in a 3 dimensional Hamiltonian lattice model of fermions. (arXiv:2306.10105v3 [cond-mat.str-el] UPDATED)
Lukasz Fidkowski, Cenke Xu

We argue that the chiral $U(1)_A$ symmetry of a Weyl fermion cannot be implemented by a shallow depth quantum circuit operation in a fermionic lattice Hamiltonian model with finite dimensional onsite Hilbert spaces. We also extend this result to discrete ${\mathbb{Z}}_{2N}$ subgroups of $U(1)_A$, in which case we show that for $N_f$ Weyl fermions of the same helicity, this group action cannot be implemented with shallow depth circuits when $N_f$ is not an integer multiple of $2N$.


Vorticity and level-set variations of invariant current bound steady-state dissipation. (arXiv:2306.13647v2 [math-ph] UPDATED)
Hao De, Aljaž Godec

A non-vanishing entropy production rate is a hallmark of non-equilibrium stationary states and is therefore at the heart of non-equilibrium thermodynamics. It is a manifestation of a steady circulation $J_{\rm inv}$ along the level sets of the invariant density $\rho_{\rm inv}$, and is thus generically used to quantify how far a steady system is driven out of equilibrium. While it is well known that there exists a continuum of distinct steady states with the same invariant measure, the question how the geometry and topology of the invariant current a priori affect dissipation remained elusive. For confined irreversible diffusions we identify two minimal descriptors, the $\rho_{\rm inv}$-weighted vorticity and the variation of $J_{\rm inv}$ along level sets of $\rho_{\rm inv}$, and prove that these jointly bound from above the steady-state entropy production rate. In regions where $\rho_{\rm inv}$ is close to Gaussian the bound is dominated solely by the vorticity of the drift field and in the low-noise (Freidlin-Wentzel) limit by any non-potential contribution to the drift, rendering $J_{\rm inv}$ virtually constant along the level sets of $\rho_{\rm inv}$.


Dissipative preparation of a Floquet topological insulator in an optical lattice via bath engineering. (arXiv:2307.03739v2 [cond-mat.quant-gas] UPDATED)
Alexander Schnell, Christof Weitenberg, André Eckardt

Floquet engineering is an important tool for realizing topologically nontrivial band structures for charge-neutral atoms in optical lattices. However, the preparation of a topological-band-insulator-type state of fermions, with one nontrivial quasi-energy band filled completely and the others empty, is challenging as a result of both driving induced heating as well as imperfect adiabatic state preparation (with the latter induced by the unavoidable gap closing when passing the topological transition). An alternative procedure that has been proposed is to prepare such states dissipatively, i.e. as a steady state that emerges when coupling the system to reservoirs. Here we discuss a concrete scheme that couples the system to a weakly interacting Bose-condensate given by second atomic species acting as a heat bath. Our strategy relies on the engineering of the potential for the bath particles, so that they occupy weakly coupled tubes perpendicular to the two-dimensional system. Using Floquet-Born-Markov theory, we show that the resulting nonequilibrium steady state of the driven-dissipative system approximates a topological insulator. We even find indications for the approximate stabilization of an anomalous Floquet topological insulator, a state that is impossible to realize in equilibrium.


Found 9 papers in prb
Date of feed: Fri, 14 Jul 2023 03:17:13 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]+)

Non-Abelian generalization of non-Hermitian quasicrystals: $\mathcal{PT}$-symmetry breaking, localization, entanglement, and topological transitions
Longwen Zhou
Author(s): Longwen Zhou

Non-Hermitian quasicrystal forms a unique class of matter with symmetry-breaking, localization and topological transitions induced by gain and loss or nonreciprocal effects. In this work, we introduce a non-Abelian generalization of non-Hermitian quasicrystal, in which the interplay between non-Herm…


[Phys. Rev. B 108, 014202] Published Thu Jul 13, 2023

Strong to weak topological interacting phase transition of bosons on a lattice
Amrita Ghosh and Eytan Grosfeld
Author(s): Amrita Ghosh and Eytan Grosfeld

We study hard-core bosons on the honeycomb lattice subjected to anisotropic nearest-neighbor hopping along with anisotropic nearest-neighbor repulsion, using a quantum Monte Carlo technique. At half filling, we find a transition from strong topological interacting order to weak topological interacti…


[Phys. Rev. B 108, 035125] Published Thu Jul 13, 2023

Multiparticle quantum walk: A dynamical probe of topological many-body excitations
Bogdan Ostahie, Doru Sticlet, Cătălin Paşcu Moca, Balázs Dóra, Miklós Antal Werner, János K. Asbóth, and Gergely Zaránd
Author(s): Bogdan Ostahie, Doru Sticlet, Cătălin Paşcu Moca, Balázs Dóra, Miklós Antal Werner, János K. Asbóth, and Gergely Zaránd

Recent experiments demonstrated that single-particle quantum walks can reveal the topological properties of single-particle states. Here, we generalize this picture to the many-body realm by focusing on multiparticle quantum walks of strongly interacting fermions. After injecting $N$ particles with …


[Phys. Rev. B 108, 035126] Published Thu Jul 13, 2023

Reversing doping asymmetry in semiconductor thin films with external voltage
Kai Liu, Zhibin Yi, and Guangfu Luo
Author(s): Kai Liu, Zhibin Yi, and Guangfu Luo

Doping asymmetry is a notable phenomenon with semiconductors and a particularly long-standing challenge limiting the applications of most wide band-gap semiconductors, which are inherent of spontaneous heavy $n$- or $p$-type doping because of their extreme band edges. This study theoretically shows …


[Phys. Rev. B 108, 035204] Published Thu Jul 13, 2023

Effects of spatial dimensionality and band tilting on the longitudinal optical conductivities in Dirac bands
Jian-Tong Hou, Chang-Xu Yan, Chao-Yang Tan, Zhi-Qiang Li, Peng Wang, Hong Guo, and Hao-Ran Chang (张浩然)
Author(s): Jian-Tong Hou, Chang-Xu Yan, Chao-Yang Tan, Zhi-Qiang Li, Peng Wang, Hong Guo, and Hao-Ran Chang (张浩然)

We report a unified theory based on linear response, for analyzing the longitudinal optical conductivity (LOC) of materials with tilted Dirac cones. Depending on the tilt parameter $t$, the Dirac electrons have four phases: untilted, type I, type II, and type III; the Dirac dispersion can be isotrop…


[Phys. Rev. B 108, 035407] Published Thu Jul 13, 2023

Local surface electronic response of ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$ topological insulator upon europium doping
Gilberto Rodrigues-Junior, Thaís Chagas, Rafael Reis, Paulo Victor Sciammarella, Celso I. Fornari, Paulo H. O. Rappl, Eduardo Abramof, Rogério Magalhães-Paniago, and Ângelo Malachias
Author(s): Gilberto Rodrigues-Junior, Thaís Chagas, Rafael Reis, Paulo Victor Sciammarella, Celso I. Fornari, Paulo H. O. Rappl, Eduardo Abramof, Rogério Magalhães-Paniago, and Ângelo Malachias

The most relevant characteristic of a topological insulator material is the presence of edge/surface states that are protected by the bulk topology, and therefore, insensitive to nonmagnetic disorder. However, if such disorder is induced by magnetic atoms or the topological insulator is subjected to…


[Phys. Rev. B 108, 035408] Published Thu Jul 13, 2023

Anomalous Hall effect in disordered Weyl semimetals
Yonatan Messica, Dmitri B. Gutman, and Pavel M. Ostrovsky
Author(s): Yonatan Messica, Dmitri B. Gutman, and Pavel M. Ostrovsky

We study the anomalous Hall effect in a disordered Weyl semimetal. While the intrinsic contribution is expressed solely in terms of Berry curvature, the extrinsic contribution is given by a combination of the skew-scattering and side-jump terms. For the model of small-size impurities, we are able to…


[Phys. Rev. B 108, 045121] Published Thu Jul 13, 2023

Modeling semiconductor spin qubits and their charge noise environment for quantum gate fidelity estimation
M. Mohamed El Kordy Shehata, George Simion, Ruoyu Li, Fahd A. Mohiyaddin, Danny Wan, Massimo Mongillo, Bogdan Govoreanu, Iuliana Radu, Kristiaan De Greve, and Pol Van Dorpe
Author(s): M. Mohamed El Kordy Shehata, George Simion, Ruoyu Li, Fahd A. Mohiyaddin, Danny Wan, Massimo Mongillo, Bogdan Govoreanu, Iuliana Radu, Kristiaan De Greve, and Pol Van Dorpe

The spin of an electron confined in semiconductor quantum dots is currently a promising candidate for quantum bit (qubit) implementations. Taking advantage of the existing CMOS integration technologies, such devices can offer a platform for large scale quantum computation. However, a quantum mechani…


[Phys. Rev. B 108, 045305] Published Thu Jul 13, 2023

Topologically distinct atomic insulators
Sanjib Kumar Das, Sourav Manna, and Bitan Roy
Author(s): Sanjib Kumar Das, Sourav Manna, and Bitan Roy

Topological classification of quantum solids often (if not always) groups all trivial atomic or normal insulators (NIs) into the same featureless family. As we argue here, this is not necessarily the case always. In particular, when the global phase diagram of electronic crystals harbors topological…


[Phys. Rev. B 108, L041301] Published Thu Jul 13, 2023

Found 3 papers in prl
Date of feed: Fri, 14 Jul 2023 03:17:12 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]+)

GRB 221009A Gamma Rays from the Radiative Decay of Heavy Neutrinos?
Alexei Y. Smirnov and Andreas Trautner
Author(s): Alexei Y. Smirnov and Andreas Trautner

We consider a mechanism that causes a decrease in the attenuation of high energy gamma-ray flux from gamma ray burst GRB 221009A. The mechanism is based on the existence of a heavy ${m}_{N}∼(0.1−1)\text{ }\text{ }\mathrm{MeV}$ mostly sterile neutrino $N$ which mixes with active neutrinos. $N$’s are …


[Phys. Rev. Lett. 131, 021002] Published Thu Jul 13, 2023

Optical Control of Slow Topological Electrons in Moiré Systems
Christopher Yang, Iliya Esin, Cyprian Lewandowski, and Gil Refael
Author(s): Christopher Yang, Iliya Esin, Cyprian Lewandowski, and Gil Refael

Floquet moiré materials possess optically-induced flat-electron bands with steady-states sensitive to drive parameters. Within this regime, we show that strong interaction screening and phonon bath coupling can overcome enhanced drive-induced heating. In twisted bilayer graphene (TBG) irradiated by …


[Phys. Rev. Lett. 131, 026901] Published Thu Jul 13, 2023

Ubiquitous Superconducting Diode Effect in Superconductor Thin Films
Yasen Hou, Fabrizio Nichele, Hang Chi, Alessandro Lodesani, Yingying Wu, Markus F. Ritter, Daniel Z. Haxell, Margarita Davydova, Stefan Ilić, Ourania Glezakou-Elbert, Amith Varambally, F. Sebastian Bergeret, Akashdeep Kamra, Liang Fu, Patrick A. Lee, and Jagadeesh S. Moodera
Author(s): Yasen Hou, Fabrizio Nichele, Hang Chi, Alessandro Lodesani, Yingying Wu, Markus F. Ritter, Daniel Z. Haxell, Margarita Davydova, Stefan Ilić, Ourania Glezakou-Elbert, Amith Varambally, F. Sebastian Bergeret, Akashdeep Kamra, Liang Fu, Patrick A. Lee, and Jagadeesh S. Moodera

A superconducting strip allows more superconducting current to flow in one direction than in the other—achieving a stronger diode effect than previous devices.


[Phys. Rev. Lett. 131, 027001] Published Thu Jul 13, 2023

Found 1 papers in pr_res
Date of feed: Fri, 14 Jul 2023 03:17:13 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]+)

Antihelical edge magnons in patterned antiferromagnetic thin films
Yun-Mei Li
Author(s): Yun-Mei Li

Helical edge states in topological insulators generate a counterpropagating spin current on the two parallel edges. We here propose antihelical edge states of magnons in patterned antiferromagnetic thin films, which host a copropagating spin current on the two parallel edges, where the two magnon mo…


[Phys. Rev. Research 5, 033026] Published Thu Jul 13, 2023

Found 1 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]+)

Scalable graphene sensor array for real-time toxins monitoring in flowing water
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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]+)

Spin fluctuations from Bogoliubov Fermi surfaces in the superconducting state of S-substituted FeSe
Naoki Fujiwara

Communications Physics, Published online: 13 July 2023; doi:10.1038/s42005-023-01286-x

Over the years the iron-based superconductors have become a platform to investigate many different phenomena such as the interplay between magnetism and superconductivity, nematicity and topological superconductivity. Here, the authors apply nuclear magnetic resonance to S-substituted FeSe in order to probe spin fluctuations, which indicate the presence of Bogoliubov Fermi surfaces.

Interference, diffraction, and diode effects in superconducting array based on bismuth antimony telluride topological insulator
Alexey Bezryadin

Communications Physics, Published online: 13 July 2023; doi:10.1038/s42005-023-01288-9

According to a recent theoretical model, Majorana bound states can induce a parity protected superconducting diode effect. Here, we fabricate an array of Nb islands on an intrinsic topological insulator, i.e., a system where Majorana bound states are expected, and observe a strong superconducting diode effect, as well as a superconducting analogue of the optical diffraction grating.