Found 28 papers in cond-mat
Date of feed: Fri, 28 Jul 2023 00:30:00 GMT

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Views on gravity from condensed matter physics. (arXiv:2307.14370v1 [cond-mat.other])
G.E. Volovik

In the paper "Life, the Universe, and everything-42 fundamental questions", Roland Allen and Suzy Lidstr\"om presented personal selection of the fundamental questions. Here, based on the condensed matter experience, we suggest the answers to some questions concerning the vacuum energy, black hole entropy and the origin of gravity.

Competition between fractional quantum Hall liquid and electron solid phases in the Landau levels of multilayer graphene. (arXiv:2307.14519v1 [cond-mat.mes-hall])
Rakesh K. Dora, Ajit C. Balram

We study the competition between the electron liquid and solid phases, such as Wigner crystal and bubbles, in partially filled Landau levels (LLs) of multilayer graphene. Graphene systems offer a versatile platform for controlling band dispersion by varying the number of its stacked layers. The band dispersion determines the LL wave functions, and consequently, the LL-projected Coulomb interaction in graphene and its multilayers is different from that in conventional semiconductors like GaAs. As a result, the energies of the liquid and solid phases are different in the different LLs of multilayer graphene, leading to a new phase diagram for the stability of these phases, which we work out. The phase diagram of competing solid and liquid phases in the LLs of monolayer graphene has been studied previously. Here, we primarily consider $AB{-}$ or Bernal$-$stacked bilayer graphene (BLG) and $ABC{-}$stacked trilayer graphene (TLG) and focus on the Laughlin fractions. We determine the cohesive energy of the solid phase using the Hartree-Fock approximation while the energy of the Laughlin liquid is computed analytically via the plasma sum rules. We find that at the Laughlin fillings, the electron liquid phase has the lowest energy among the phases considered in the $\mathcal{N}{=}0, 1, 2$ LLs of BLG, as well as in the $\mathcal{N}{=}3, 4$ LLs of TLG, while in the $\mathcal{N}{>}2$ LLs of BLG and $\mathcal{N}{>}4$ LLs of TLG, the solid phases are more favorable. We also discuss the effect of impurities on the above-mentioned phase diagram.

Twist-angle and thickness-ratio tuning of plasmon polaritons in twisted bilayer van der Waals films. (arXiv:2307.14586v1 [physics.optics])
Chong Wang, Yuangang Xie, Junwei Ma, Guangwei Hu, Qiaoxia Xing, Shenyang Huang, Chaoyu Song, Fanjie Wang, Yuchen Lei, Jiasheng Zhang, Lei Mu, Tan Zhang, Yuan Huang, Cheng-Wei Qiu, Yugui Yao, Hugen Yan

Stacking bilayer structures is an efficient way to tune the topology of polaritons in in-plane anisotropic films, e.g., by leveraging the twist angle (TA). However, the effect of another geometric parameter, film thickness ratio (TR), on manipulating the plasmon topology in bilayers is elusive. Here, we fabricate bilayer structures of WTe2 films, which naturally host in-plane hyperbolic plasmons in the terahertz range. Plasmon topology is successfully modified by changing the TR and TA synergistically, manifested by the extinction spectra of unpatterned films and the polarization dependence of the plasmon intensity measured in skew ribbon arrays. Such TR- and TA-tunable topological transitions can be well explained based on the effective sheet optical conductivity by adding up those of the two films. Our study demonstrates TR as another degree of freedom for the manipulation of plasmonic topology in nanophotonics, exhibiting promising applications in bio-sensing, heat transfer and the enhancement of spontaneous emission.

Spin-orbit torque emerging from orbital textures in centrosymmetric materials. (arXiv:2307.14673v1 [cond-mat.mes-hall])
Luis M. Canonico, Jose H. García, Stephan Roche

We unveil a hitherto concealed spin-orbit torque mechanism driven by orbital degrees of freedom in centrosymmetric two-dimensional transition metal dichalcogenides (focusing on PtSe${}_2$ ). Using first-principles simulations, tight-binding models and large-scale quantum transport calculations, we show that such a mechanism fundamentally stems from a spatial localization of orbital textures at opposite sides of the material, which imprints their symmetries onto spin-orbit coupling effects, further producing efficient and tunable spin-orbit torque. Our study suggests that orbital-spin entanglement at play in centrosymmetric materials can be harnessed as a resource for outperforming conventional spin-orbit torques generated by the Rashba-type effects.

Broadband parametric amplification for multiplexed SiMOS quantum dot signals. (arXiv:2307.14717v1 [cond-mat.mes-hall])
Victor Elhomsy, Luca Planat, David J. Niegemann, Bruna Cardoso-Paz, Ali Badreldin, Bernhard Klemt, Vivien Thiney, Renan Lethiecq, Eric Eyraud, Matthieu C. Dartiailh, Benoit Bertrand, Heimanu Niebojewski, Christopher Bäuerle, Maud Vinet, Tristan Meunier, Nicolas Roch, Matias Urdampilleta

Spins in semiconductor quantum dots hold great promise as building blocks of quantum processors. Trapping them in SiMOS transistor-like devices eases future industrial scale fabrication. Among the potentially scalable readout solutions, gate-based dispersive radiofrequency reflectometry only requires the already existing transistor gates to readout a quantum dot state, relieving the need for additional elements. In this effort towards scalability, traveling-wave superconducting parametric amplifiers significantly enhance the readout signal-to-noise ratio (SNR) by reducing the noise below typical cryogenic low-noise amplifiers, while offering a broad amplification band, essential to multiplex the readout of multiple resonators. In this work, we demonstrate a 3GHz gate-based reflectometry readout of electron charge states trapped in quantum dots formed in SiMOS multi-gate devices, with SNR enhanced thanks to a Josephson traveling-wave parametric amplifier (JTWPA). The broad, tunable 2GHz amplification bandwidth combined with more than 10dB ON/OFF SNR improvement of the JTWPA enables frequency and time division multiplexed readout of interdot transitions, and noise performance near the quantum limit. In addition, owing to a design without superconducting loops and with a metallic ground plane, the JTWPA is flux insensitive and shows stable performances up to a magnetic field of 1.2T at the quantum dot device, compatible with standard SiMOS spin qubit experiments.

Real-space topological localizer index to fully characterize the dislocation skin effect. (arXiv:2307.14753v1 [cond-mat.mes-hall])
Nisarg Chadha, Ali G. Moghaddam, Jeroen van den Brink, Cosma Fulga

The dislocation skin effect exhibits the capacity of topological defects to trap an extensive number of modes in two-dimensional non-Hermitian systems. Similar to the corresponding skin effects caused by system boundaries, this phenomenon also originates from nontrivial topology. However, finding the relationship between the dislocation skin effect and nonzero topological invariants, especially in disordered systems, can be obscure and challenging. Here, we introduce a real-space topological invariant based on the spectral localizer to characterize the skin effect on two-dimensional lattices. We demonstrate that this invariant consistently predicts the occurrence and location of both boundary and dislocation skin effects, offering a unified approach applicable to both ordered and disordered systems. Our work demonstrates a general approach that can be utilized to diagnose the topological nature of various types of skin effects, particularly in the absence of translational symmetry when momentum-space descriptions are inapplicable.

Emerging topological bound states in Haldane model zigzag nanoribbons. (arXiv:2307.14771v1 [cond-mat.mes-hall])
Simone Traverso, Maura Sassetti, Niccolò Traverso Ziani

Zigzag nanoribbons hosting the Haldane Chern insulator model are considered. In this context, an unreported reentrant topological phase, characterized by the emergence of quasi zero dimensional in-gap states, is discussed. The bound states, which reside in the gap opened by the hybridization of the counter-propagating edge modes of the Haldane phase, are localized at the ends of the strip and are found to be robust against on-site disorder. These findings are supported by the behavior of the Zak phase over the parameter space, which exhibits jumps of $\pi$ in correspondence to the phase transitions between the trivial and the non-trivial phases. Setups with non-uniform parameters also show topological bound states via the Jackiw-Rebbi mechanism. All the properties reported are shown to be extremely sensitive to the strip width.

Understanding magnetoelectric switching in BiFeO$_3$ thin films. (arXiv:2307.14789v1 [cond-mat.mtrl-sci])
Natalya S. Fedorova, Dmitri E. Nikonov, John M. Mangeri, Hai Li, Ian A. Young, Jorge Íñiguez

In this work we use a phenomenological theory of ferroelectric switching in BiFeO$_3$ thin films to uncover the mechanism of the two-step process that leads to the reversal of the weak magnetization of these materials. First, we introduce a realistic model of a BiFeO$_3$ film, including the Landau energy of isolated domains as well as the constraints that account for the presence of the substrate and the multidomain configuration found experimentally. We use this model to obtain statistical information about the switching behavior - by running dynamical simulations based on the Landau-Khalatnikov time-evolution equation, including thermal fluctuations - and we thus identify the factors that drive the two-step polarization reversal observed in the experiments. Additionally, we apply our model to test potential strategies for optimizing the switching characteristics.

Solid lubrication by wet-transferred solution-processed graphene flakes: dissipation mechanisms and superlubricity in mesoscale contacts. (arXiv:2307.14813v1 [cond-mat.mes-hall])
Renato Buzio, Andrea Gerbi, Cristina Bernini, Luca Repetto, Andrea Silva, Andrea Vanossi

Solution-processed few-layers graphene flakes, dispensed to rotating and sliding contacts via liquid dispersions, are gaining increasing attention as friction modifiers to achieve low friction and wear at technologically-relevant interfaces. Vanishing friction states, i.e. superlubricity, have been documented for nearly-ideal nanoscale contacts lubricated by individual graphene flakes; there is however no clear understanding if superlubricity might persist for larger and morphologically-disordered contacts, as those typically obtained by graphene wet transfer from a liquid dispersion. In this study we address the friction performance of solution-processed graphene flakes by means of colloidal probe Atomic Force Microscopy. We use an additive-free aqueous dispersion to coat micrometric silica beads, which are then sled under ambient conditions against prototypical material substrates, namely graphite and the transition metal dichalcogenides (TMDs) MoS2 and WS2. High resolution microscopy proves that the random assembly of the wet-transferred flakes over the silica probes results into an inhomogeneous coating, formed by graphene patches that control contact mechanics through tens-of-nanometers tall protrusions. Atomic-scale friction force spectroscopy reveals that dissipation proceeds via stick-slip instabilities. Load-controlled transitions from dissipative stick-slip to superlubric continuous sliding may occur for the graphene-graphite homojunctions, whereas single- and multiple-slips dissipative dynamics characterizes the graphene-TMD heterojunctions. Systematic numerical simulations demonstrate that the thermally-activated single-asperity Prandtl-Tomlinson model comprehensively describes friction experiments involving different graphene-coated colloidal probes, material substrates and sliding regimes.

Topological superconductivity with large Chern numbers in a ferromagnetic metal-superconductor heterostructure. (arXiv:2307.14838v1 [cond-mat.supr-con])
Yingwen Zhang, Dao-Xin Yao, Zhi Wang

The ferromagnetic metal-superconductor heterostructure with interface Rashba spin-orbit hopping is a promising candidate for topological superconductivity. We study the interplay between the interface Rashba hopping and the intrinsic Dresselhaus spin-orbit coupling in this heterostructure, and demonstrate rich topological phases with five distinct Chern numbers. In particular, we find a topological state with a Chern number as large as four in the parameter space of the heterostructure. We calculate the Berry curvatures that construct the Chern numbers, and show that these Berry curvatures induce anomalous thermal Hall transport of the superconducting quasiparticles. We reveal chiral edge states in the topological phases, as well as helical edge states in the trivial phase, and show that the wave functions of these edge states mostly concentrate on the ferrometal layer of the heterostructure.

Eigenenergy braids in 2D photonic crystals. (arXiv:2307.14845v1 [physics.optics])
Janet Zhong, Charles C. Wojcik, Dali Cheng, Shanhui Fan

We consider non-Hermitian energy band theory in two-dimensional systems, and study eigenenergy braids on slices in the two-dimensional Brillouin zone. We show the consequences of reciprocity and geometric symmetry on such eigenenergy braids. The point-gap topology of the energy bands can be found from the projection of the eigenenergy braid onto the complex energy plane. We show that the conjugacy class transitions in the eigenenergy braid results in the changes in the number of bands in a complete point-gap loop. This transition occurs at exceptional points. We numerically demonstrate these concepts using two-dimensional reciprocal and nonreciprocal photonic crystals.

Anisotropic multiband superconductivity in 2M-WS$_{2}$ probed by controlled disorder. (arXiv:2307.14891v1 [cond-mat.supr-con])
Sunil Ghimire, Kamal R. Joshi, Marcin Konczykowski, Romain Grasset, Amlan Datta, Makariy A. Tanatar, Damien Berube, Su-Yang Xu, Yuqiang Fang, Fuqiang Huang, Peter P. Orth, Mathias S. Scheurer, Ruslan Prozorov

The intrinsically superconducting Dirac semimetal 2M-WS$_{2}$ is a promising candidate to realize proximity-induced topological superconductivity in its protected surface states. A precise characterization of the bulk superconducting state is essential for understanding the nature of surface superconductivity in the system. Here, we perform a detailed experimental study of the temperature and nonmagnetic disorder dependence of the London penetration depth $\lambda$, the upper critical field $H_{c2}$, and the superconducting transition temperature $T_c$ in 2M-WS$_{2}$. We observe a power-law dependence $\lambda(T) - \lambda(0) \propto T^{3}$ at temperatures below $0.35~T_c$, which is remarkably different from the expected exponential attenuation of a fully gapped isotropic $s$-wave superconductor. We then probe the effect of controlled nonmagnetic disorder induced by 2.5 MeV electron irradiation at various doses and find a significant $T_c$ suppression rate. Together with the observed increase of the slope $dH_{c2}/dT|_{T=T_c}$ with irradiation, our results reveal a strongly anisotropic $s^{++}$ multiband superconducting state that takes the same sign on different Fermi sheets. Our results have direct consequences for the expected proximity-induced superconductivity of the topological surface states.

The structure of disintegrating defect clusters in smectic C freely suspended films. (arXiv:2307.14937v1 [cond-mat.soft])
Ralf Stannarius, Kirsten Harth

Disclinations or disclination clusters in smectic C freely suspended films with topological charges larger than one are unstable. They disintegrate, preferably in a spatially symmetric fashion, into single defects with individual charges +1, which is the smallest positive topological charge allowed in polar vector fields. While the opposite process of defect annihilation is well-defined by the initial defect positions, a disintegration starts from a singular state and the following scenario including the emerging regular defect patterns must be selected by specific mechanisms. We analyze experimental data and compare them with a simple model where the defect clusters adiabatically pass quasi-equilibrium solutions in one-constant approximation. It is found that the defects arrange in geometrical patterns that correspond very closely to superimposed singular defect solutions, without additional director distortions. The patterns expand by affine transformations where all distances between individual defects scale with the same time-dependent scaling factor proportional to the square-root of time.

Spectroscopy and topological properties of a Haldane light system. (arXiv:2307.14960v1 [cond-mat.mes-hall])
Julian Legendre, Karyn Le Hur

We present a method to probe the topological properties of a circuit quantum electrodynamics (cQED) array described through a Haldane model on the honeycomb lattice. We develop the theory of microwave light propagating in a local probe or a microscope (a one-dimensional transmission line) capacitively coupled to the topological cQED lattice model. Interestingly, we show that even if the microwave light has no transverse polarization, the measured reflection coefficient, resolved in frequency through the resonance, allows us to reveal the geometrical properties and topological phase transition associated to the model. This spectroscopy tool developed for cQED lattice models reveals the same topological information as circularly polarized light, locally within the Brillouin zone of the honeycomb lattice. Furthermore, our findings hold significance for topological magnon systems and are a priori applicable to all Chern insulators, presenting an intriguing opportunity for their adaptation to other systems with different particle statistics.

Higher-order Topological Insulators and Semimetals in Three Dimensions without Crystalline Counterparts. (arXiv:2307.14974v1 [cond-mat.mes-hall])
Yu-Feng Mao, Yu-Liang Tao, Jiong-Hao Wang, Qi-Bo Zeng, Yong Xu

Quasicrystals allow for symmetries that are impossible in crystalline materials, such as eight-fold rotational symmetry, enabling the existence of novel higher-order topological insulators in two dimensions without crystalline counterparts. However, it remains an open question whether three-dimensional higher-order topological insulators and Weyl-like semimetals without crystalline counterparts can exist. Here, we demonstrate the existence of a second-order topological insulator by constructing and exploring a three-dimensional model Hamiltonian in a stack of Ammann-Beenker tiling quasicrystalline lattices. The topological phase has eight chiral hinge modes that lead to quantized longitudinal conductances of $4 e^2/h$. We show that the topological phase is characterized by the winding number of the quadrupole moment. We further establish the existence of a second-order topological insulator with time-reversal symmetry, characterized by a $\mathbb{Z}_2$ topological invariant. Finally, we propose a model that exhibits a higher-order Weyl-like semimetal phase, demonstrating both hinge and surface Fermi arcs. Our findings highlight that quasicrystals in three dimensions can give rise to higher-order topological insulators and semimetal phases that are unattainable in crystals.

Helical Separation Effect and helical heat transport for Dirac fermions. (arXiv:2307.14987v1 [hep-th])
Victor E. Ambruş, Maxim N. Chernodub

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

Unpinned Dirac-Fermions in Carbon-Phosphorous-Arsenic Based Ternary Monolayer. (arXiv:2307.15001v1 [cond-mat.mtrl-sci])
Amrendra Kumar, C. Kamal

We predict energetically and dynamically stable ternary Carbon-Phosphorous-Arsenic (CPAs2) monolayers in buckled geometric structure by employing density functional theory based calculations. We consider three different symmetric configurations, namely, inversion (i), mirror (m) and rotational (r). The low-energy dispersions in electronic band structure and density of states (DOS) around the Fermi level contain two contrasting features: (a) parabolic dispersion around highly symmetric Gamma point with a step function in DOS due to nearly-free-particle-like Schroedinger-Fermions and (b) linear dispersion around highly symmetric K point with linear DOS due to massless Dirac-Fermions for i-CPAs2 monolayer. The step function in DOS is a consequence of two-dimensionality of the system in which the motion of nearly-free-particles is confined. However, a closer look at (b) reveals that the ternary monolayers possess distinct characters, namely (i) massless-gapless, (ii) slightly massive-gapped and (iii) unpinned massless-gapless Dirac-Fermions for i, m and r-CPAs2 configurations respectively. Thus, the nature of states around the Fermi level depends crucially on the symmetry of systems. In addition, we probe the influence of mechanical strain on the properties of CPAs2 monolayer. The results indicate that the characteristic dispersions of (a) and (b) move in opposite directions in energy which leads to a metal-to-semimetal transition in i and r-CPAs2 configurations, for a few percentages of tensile strain. On the other hand, a strain induced metal-to-semiconductor transition is observed in m-CPAs2 configuration with a tunable energy band gap. Interestingly, unlike graphene, the Dirac cones can be unpinned from highly symmetric K (and K') point, but they are restricted to move along the edges (K-M'-K') of first Brillouin zone due to C2 symmetry in i and r-CPAs2 configurations.

PolyHoop: Soft particle and tissue dynamics with topological transitions. (arXiv:2307.15006v1 [cond-mat.soft])
Roman Vetter, Steve V. M. Runser, Dagmar Iber

We present PolyHoop, a lightweight standalone C++ implementation of a mechanical model to simulate the dynamics of soft particles and cellular tissues in two dimensions. With only few geometrical and physical parameters, PolyHoop is capable of simulating a wide range of particulate soft matter systems: from biological cells and tissues to vesicles, bubbles, foams, emulsions, and other amorphous materials. The soft particles or cells are represented by continuously remodeling, non-convex, high-resolution polygons that can undergo growth, division, fusion, aggregation, and separation. With PolyHoop, a tissue or foam consisting of a million cells with high spatial resolution can be simulated on conventional laptop computers.

Learnability transitions in monitored quantum dynamics via eavesdropper's classical shadows. (arXiv:2307.15011v1 [quant-ph])
Matteo Ippoliti, Vedika Khemani

Monitored quantum dynamics -- unitary evolution interspersed with measurements -- has recently emerged as a rich domain for phase structure in quantum many-body systems away from equilibrium. Here we study monitored dynamics from the point of view of an eavesdropper who has access to the classical measurement outcomes, but not to the quantum many-body system. We show that a measure of information flow from the quantum system to the classical measurement record -- the informational power -- undergoes a phase transition in correspondence with the measurement-induced phase transition (MIPT). This transition determines the eavesdropper's (in)ability to learn properties of an unknown initial quantum state of the system, given a complete classical description of the monitored dynamics and arbitrary classical computational resources. We make this learnability transition concrete by defining classical shadows protocols that the eavesdropper may apply to this problem, and show that the MIPT manifests as a transition in the sample complexity of various shadow estimation tasks, which become harder in the low-measurement phase. We focus on three applications of interest: Pauli expectation values (where we find the MIPT appears as a point of optimal learnability for typical Pauli operators), many-body fidelity, and global charge in $U(1)$-symmetric dynamics. Our work unifies different manifestations of the MIPT under the umbrella of learnability and gives this notion a general operational meaning via classical shadows.

Bridging three-dimensional coupled-wire models and cellular topological states: Solvable models for topological and fracton orders. (arXiv:2112.07926v2 [cond-mat.str-el] UPDATED)
Yohei Fuji, Akira Furusaki

Three-dimensional (3d) gapped topological phases with fractional excitations are divided into two subclasses: one has topological order with point-like and loop-like excitations fully mobile in the 3d space, and the other has fracton order with point-like excitations constrained in lower-dimensional subspaces. These exotic phases are often studied by exactly solvable Hamiltonians made of commuting projectors, which, however, are not capable of describing those with chiral gapless surface states. Here we introduce a systematic way, based on cellular construction recently proposed for 3d topological phases, to construct another type of exactly solvable models in terms of coupled quantum wires with given inputs of cellular structure, two-dimensional Abelian topological order, and their gapped interfaces. We show that our models can describe both 3d topological and fracton orders (and even their hybrid) and study their universal properties such as quasiparticle statistics and topological ground-state degeneracy. We also apply this construction to two-dimensional coupled-wire models with ordinary topological orders and translation-symmetry-enriched topological orders. Our results pave the way for effective quantum field theory descriptions or microscopic model realizations of fracton orders with chiral gapless surface states.

Multi-scale time-resolved electron diffraction: A case study in moir\'e materials. (arXiv:2206.08404v2 [physics.ins-det] UPDATED)
C. J. R. Duncan, M. Kaemingk, W. H. Li, M. B. Andorf, A. C. Bartnik, A. Galdi, M. Gordon, C. A. Pennington, I. V. Bazarov, H. J. Zeng, F. Liu, D. Luo, A. Sood, A. M. Lindenberg, M. W. Tate, D. A. Muller, J. Thom-Levy, S. M. Gruner, J. M. Maxson

Ultrafast-optical-pump -- structural-probe measurements, including ultrafast electron and x-ray scattering, provide direct experimental access to the fundamental timescales of atomic motion, and are thus foundational techniques for studying matter out of equilibrium. High-performance detectors are needed in scattering experiments to obtain maximum scientific value from every probe particle. We deploy a hybrid pixel array direct electron detector to perform ultrafast electron diffraction experiments on a WSe$_2$/MoSe$_2$ 2D heterobilayer, resolving the weak features of diffuse scattering and moir\'e superlattice structure without saturating the zero order peak. Enabled by the detector's high frame rate, we show that a chopping technique provides diffraction difference images with signal-to-noise at the shot noise limit. Finally, we demonstrate that a fast detector frame rate coupled with a high repetition rate probe can provide continuous time resolution from femtoseconds to seconds, enabling us to perform a scanning ultrafast electron diffraction experiment that maps thermal transport in WSe$_2$/MoSe$_2$ and resolves distinct diffusion mechanisms in space and time.

Revealing temperature evolution of the Dirac band in ZrTe$_5$ via magneto-infrared spectroscopy. (arXiv:2211.16711v2 [cond-mat.mtrl-sci] UPDATED)
Yuxuan Jiang, Tianhao Zhao, Luojia Zhang, Qiang Chen, Haidong Zhou, Mykhaylo Ozerov, Dmitry Smirnov, Zhigang Jiang

We report the temperature evolution of the Dirac band in semiconducting zirconium pentatelluride (ZrTe$_5$) using magneto-infrared spectroscopy. We find that the band gap is temperature independent at low temperatures and increases with temperature at elevated temperatures. Although such an observation seems to support a weak topological insulator phase at all temperatures and defy the previously reported topological phase transition (TPT) at an intermediate temperature in ZrTe$_5$, we show that it is also possible to explain the observation by considering the effect of conduction-valence band mixing and band inversion with a strong topological insulator phase at low temperatures. Our work provides an alternative picture of the band gap evolution across TPT.

Renormalization of Ising cage-net model and generalized foliation. (arXiv:2301.00103v2 [cond-mat.str-el] UPDATED)
Zongyuan Wang, Xiuqi Ma, David T. Stephen, Michael Hermele, Xie Chen

A large class of type-I fracton models, including the X-cube model, have been found to be fixed points of the foliated renormalization group (RG). The system size of such foliated models can be changed by adding or removing decoupled layers of $2$D topological states and continuous deformation of the Hamiltonian. In this paper, we study a closely related model -- the Ising cage-net model -- and find that this model is not foliated in the same sense. In fact, we point out certain unnatural restrictions in the foliated RG, and find that removing these restrictions leads to a generalized foliated RG under which the Ising cage-net model is a fixed point, and which includes the original foliated RG as a special case. The Ising cage-net model thus gives a prototypical example of the generalized foliated RG, and its system size can be changed either by condensing / uncondensing bosonic planon excitations near a 2D plane or through a linear depth quantum circuit in the same plane. We show that these two apparently different RG procedures are closely related, as they lead to the same gapped boundary when implemented in part of a plane. Finally, we briefly discuss the implications for foliated fracton phases, whose universal properties will need to be reexamined in light of the generalized foliated RG.

Bohm - de Broglie Cycles. (arXiv:2301.13251v2 [quant-ph] UPDATED)
Olivier Piguet

In the de Broglie-Bohm quantum theory, particles describe trajectories determined by the flux associated with their wave function. These trajectories are studied here for relativistic spin-one-half particles.Based in explicit numerical calculations for the case of a massless particle in dimension three space-time, it is shown that if the wave function is an eigenfunction of the total angular momentum, the trajectories begin as circles of slowly increasing radius until a transition time at which they tend to follow straight lines. Arrival times at some detector, as well as their probability distribution are calculated, too. The chosen energy and momentum parameters are of the orders of magnitude met in graphene's physics.

Hamiltonian cycles on Ammann-Beenker Tilings. (arXiv:2302.01940v3 [cond-mat.stat-mech] UPDATED)
Shobhna Singh, Jerome Lloyd, Felix Flicker

We provide a simple algorithm for constructing Hamiltonian graph cycles (visiting every vertex exactly once) on the set of aperiodic two-dimensional Ammann-Beenker (AB) tilings. Using this result, and the discrete scale symmetry of AB tilings, we find exact solutions to a range of other problems which lie in the complexity class NP-Complete for general graphs. These include the equal-weight travelling salesperson problem, providing for example the most efficient route a scanning tunneling microscope tip could take to image the atoms of physical quasicrystals with AB symmetries; the longest path problem, whose solution demonstrates that collections of flexible molecules of any length can adsorb onto AB quasicrystal surfaces at density one, with possible applications to catalysis; and the 3-colouring problem, giving ground states for the $q$-state Potts model ($q\ge 3$) of magnetic interactions defined on the planar dual to AB, which may provide useful models for protein folding.

Theory of resonantly enhanced photo-induced superconductivity. (arXiv:2303.02176v2 [cond-mat.supr-con] UPDATED)
Christian J. Eckhardt, Sambuddha Chattopadhyay, Dante M. Kennes, Eugene A. Demler, Michael A. Sentef, Marios H. Michael

Optical driving of materials has emerged as a versatile tool to control their properties, with photo-induced superconductivity being among the most fascinating examples. In this work, we show that light or lattice vibrations coupled to an electronic interband transition naturally give rise to electron-electron attraction that may be enhanced when the underlying boson is driven into a non-thermal state. We find this phenomenon to be resonantly amplified when tuning the boson's frequency close to the energy difference between the two electronic bands. This result offers a simple microscopic mechanism for photo-induced superconductivity and provides a recipe for designing new platforms in which light-induced superconductivity can be realized. We propose a concrete setup consisting of a graphene-hBN-SrTiO$_3$ heterostructure, for which we estimate a superconducting $T_{\rm c}$ that may be achieved upon driving the system.

Topological paramagnetic excitons of localized f electrons on the honeycomb lattice. (arXiv:2303.17975v2 [cond-mat.str-el] UPDATED)
Alireza Akbari, Burkhard Schmidt, Peter Thalmeier

We investigate the dispersive paramagnetic excitons on the honeycomb lattice that originate from the crystalline-electric field (CEF) split localized f-electron states in the paramagnetic state due to intersite exchange. We start with a symmetry analysis of possible Ising-type singlet-singlet and xy-type singlet-doublet models. The former supports only symmetric intersite-exchange while the latter additionally allows for antisymmetric Dzyaloshinski-Moriya (DM) exchange interactions. We calculate the closed expressions for magnetic exciton dispersion using both response function formalism and the bosonic Bogoliubov approach. We do this for the most general model that shows inversion symmetry breaking on the honeycomb lattice but also discuss interesting special cases. By calculating Berry curvatures and Chern numbers of paramagnetic excitons we show that the xy model supports nontrivial topological states in a wide range of parameters. This leads to the existence of excitonic topological edge states with Dirac dispersion lying in the zone boundary gap without the presence of magnetic order.

A Zero-Threshold PT-Symmetric Polariton-Raman Laser. (arXiv:2305.17475v3 [cond-mat.mes-hall] UPDATED)
Avijit Dhara, Devarshi Chakrabarty, Pritam Das, Kritika Ghosh, Ayan Roy Chaudhuri, Sajal Dhara

Parity-time (PT)-symmetry in the classical regime has been realized in optics by introducing loss and gain in electromagnetic wave propagation which has yielded numerous applications like nonreciprocal propagation and finite threshold single-mode lasers. However, PT-symmetry in the quantum regime so far remains elusive. Here, we demonstrate a PT-symmetric zero-threshold polariton-Raman laser by utilizing stimulated resonant Raman scattering of polarized exciton-polaritons. By pumping resonantly at the exceptional point of polariton bands with non-Hermitian topology, a quantum PT-symmetric phase is realized when the Raman-active phonon mode frequencies match with the polariton mode frequency difference. The PT-symmetric phase corresponding to zero-threshold lasing can be switched to PT broken phase showing a finite threshold via cavity detuning by the variation of bath temperature or pump polarization. Our realization of PT-symmetry in the quantum regime and consequently the zero-threshold laser can open up applications in quantum information and stimulate new research activities in cavity quantum electrodynamics.

Found 5 papers in prb
Date of feed: Fri, 28 Jul 2023 03:17:06 GMT

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

From topological phase to transverse Anderson localization in a two-dimensional quasiperiodic system
Shujie Cheng, Reza Asgari, and Gao Xianlong
Author(s): Shujie Cheng, Reza Asgari, and Gao Xianlong

In this paper, we provide theoretical approaches to identify the influence of the quasidisorder on a two-dimensional system. We discover that in the system there is a topological phase transition accompanied by a transverse Anderson localization. The topological features are characterized by the ban…

[Phys. Rev. B 108, 024204] Published Thu Jul 27, 2023

Tunable properties of excitons in double monolayer semiconductor heterostructures
Luiz G. M. Tenório, Teldo A. S. Pereira, K. Mohseni, T. Frederico, M. R. Hadizadeh, Diego R. da Costa, and André J. Chaves
Author(s): Luiz G. M. Tenório, Teldo A. S. Pereira, K. Mohseni, T. Frederico, M. R. Hadizadeh, Diego R. da Costa, and André J. Chaves

We studied the exciton properties in double layers of transition metal dichalcogenides (TMDs) with a dielectric spacer between the layers. We developed a method based on an expansion of Chebyshev polynomials to solve the Wannier equation for the exciton. Corrections to the quasiparticle bandgap due …

[Phys. Rev. B 108, 035421] Published Thu Jul 27, 2023

Triply degenerate topological phase and stretchable Fermi arc surface states in gyromagnetic metamaterials
Mingzhu Li, Ning Han, Lu Qi, and Liang Peng
Author(s): Mingzhu Li, Ning Han, Lu Qi, and Liang Peng

Triple-fold band degeneracy (TBD) is an intriguing phase of topological semimetals which appears as the intermediate state between the four-folded degenerated Dirac points and the two-folded Weyl points. The resemblance of TBD in the photonics is interesting, because it indicates nonzero Berry curva…

[Phys. Rev. B 108, 035422] Published Thu Jul 27, 2023

Theory of the anomalous Hall effect in the transition metal pentatellurides ${\mathrm{ZrTe}}_{5}$ and ${\mathrm{HfTe}}_{5}$
Huan-Wen Wang, Bo Fu, and Shun-Qing Shen
Author(s): Huan-Wen Wang, Bo Fu, and Shun-Qing Shen

The anomalous Hall effect has considerable impact on the progress of condensed matter physics and occurs in systems with time-reversal symmetry breaking. Here we theoretically investigate the anomalous Hall effect in the nonmagnetic transition metal pentatellurides ${\mathrm{ZrTe}}_{5}$ and ${\mathr…

[Phys. Rev. B 108, 045141] Published Thu Jul 27, 2023

Topological paramagnetic excitons of localized $f$ electrons on the honeycomb lattice
Alireza Akbari, Burkhard Schmidt, and Peter Thalmeier
Author(s): Alireza Akbari, Burkhard Schmidt, and Peter Thalmeier

We investigate the dispersive paramagnetic excitons on the honeycomb lattice that originate from the crystalline electric field split localized $f$-electron states in the paramagnetic state due to intersite exchange. We start with a symmetry analysis of possible Ising-type singlet-singlet and $xy$-t…

[Phys. Rev. B 108, 045143] Published Thu Jul 27, 2023

Found 2 papers in prl
Date of feed: Fri, 28 Jul 2023 03:17:05 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]+)

Zeeman Field-Induced Two-Dimensional Weyl Semimetal Phase in Cadmium Arsenide
Binghao Guo, Wangqian Miao, Victor Huang, Alexander C. Lygo, Xi Dai, and Susanne Stemmer
Author(s): Binghao Guo, Wangqian Miao, Victor Huang, Alexander C. Lygo, Xi Dai, and Susanne Stemmer

We report a topological phase transition in quantum-confined cadmium arsenide (${\mathrm{Cd}}_{3}{\mathrm{As}}_{2}$) thin films under an in-plane Zeeman field when the Fermi level is tuned into the topological gap via an electric field. Symmetry considerations in this case predict the appearance of …

[Phys. Rev. Lett. 131, 046601] Published Thu Jul 27, 2023

Nonmonotonous Translocation Time of Polymers across Pores
Emanuele Locatelli, Valentino Bianco, Chantal Valeriani, and Paolo Malgaretti
Author(s): Emanuele Locatelli, Valentino Bianco, Chantal Valeriani, and Paolo Malgaretti

The translocation time of linear polymers across a varying-section channel shows a nonmonotonous dependence on the polymer size, that may be a useful tool to design channels for polymer sorting.

[Phys. Rev. Lett. 131, 048101] Published Thu Jul 27, 2023

Found 1 papers in nano-lett
Date of feed: Thu, 27 Jul 2023 13:10:47 GMT

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

[ASAP] Fluctuations in Planar Magnetotransport Due to Tilted Dirac Cones in Topological Materials
Arya Thenapparambil, Graciely Elias dos Santos, Chang-An Li, Mohamed Abdelghany, Wouter Beugeling, Hartmut Buhmann, Charles Gould, Song-Bo Zhang, Björn Trauzettel, and Laurens W. Molenkamp

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Nano Letters
DOI: 10.1021/acs.nanolett.3c01508

Found 2 papers in acs-nano
Date of feed: Thu, 27 Jul 2023 13:07:47 GMT

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

[ASAP] A Surfactant-Free and General Strategy for the Synthesis of Bimetallic Core–Shell Nanocrystals on Reduced Graphene Oxide through Targeted Photodeposition
Yidan Liu, Yali Ji, Qian Li, Yi Zhu, Jianchao Peng, Rongrong Jia, Zhuangchai Lai, Liyi Shi, Fengtao Fan, Gengfeng Zheng, Lei Huang, and Can Li

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ACS Nano
DOI: 10.1021/acsnano.3c04281

[ASAP] Effects of Floquet Engineering on the Coherent Exciton Dynamics in Monolayer WS2
Mitchell A. Conway, Stuart K. Earl, Jack B. Muir, Thi-Hai-Yen Vu, Jonathan O. Tollerud, Kenji Watanabe, Takashi Taniguchi, Michael S. Fuhrer, Mark T. Edmonds, and Jeffrey A. Davis

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ACS Nano
DOI: 10.1021/acsnano.3c01318