Found 38 papers in cond-mat
Date of feed: Wed, 20 Dec 2023 01:30:00 GMT

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Tracking Intrinsic Non-Hermitian Skin Effect in Lossy Lattices. (arXiv:2312.11490v1 [cond-mat.other])
Liwei Xiong, Qicheng Zhang, Xiling Feng, Yufei Leng, Min Pi, Shuaishuai Tong, Chunyin Qiu

Non-Hermitian skin effect (NHSE), characterized by a majority of eigenstates localized at open boundaries, is one of the most iconic phenomena in non-Hermitian lattices. Despite notable experimental studies implemented, most of them witness only certain signs of the NHSE rather than the intrinsic exponential localization inherent in eigenstates, owing to the ubiquitous and inevitable background loss. Even worse, the experimental observation of the NHSE would be completely obscured in highly lossy cases. Here, we theoretically propose a dual test approach to eliminate the destructive loss effect and track the intrinsic NHSE that is essentially irrelevant to background loss. Experimentally, the effectiveness of this approach is precisely validated by one- and two-dimensional non-Hermitian acoustic lattices. Our study sheds new light on the previously untapped intrinsic aspect of the NHSE, which is of particular significance in non-Hermitian topological physics.


Essay: Where Can Quantum Geometry Lead Us?. (arXiv:2312.11516v1 [cond-mat.supr-con])
Paivi Torma

Quantum geometry defines the phase and amplitude distances between quantum states. The phase distance is characterized by the Berry curvature and thus relates to topological phenomena. The significance of the full quantum geometry, including the amplitude distance characterized by the quantum metric, has started to receive attention in the last few years. Various quantum transport and interaction phenomena have been found to be critically influenced by quantum geometry. For example, quantum geometry allows counterintuitive flow of supercurrent in a flat band where single electrons are immobile. In this Essay, I will discuss my view of the important open problems and future applications of this research topic and will try to inspire the reader to come up with further ideas. At its best, quantum geometry can open a new chapter in band theory and lead to breakthroughs as transformative as room-temperature superconductivity. However, first, more experiments directly showing the effect of quantum geometry are needed. We also have to integrate quantum geometry analysis in our most advanced numerical methods. Further, the ramifications of quantum geometry should be studied in a wider range, including electric and electromagnetic responses and interaction phenomena in free- and correlated-electron materials, bosonic systems, optics, and other fields.


Phenomenology of Majorana zero modes in full-shell hybrid nanowires. (arXiv:2312.11613v1 [cond-mat.mes-hall])
Carlos Payá, Samuel D. Escribano, Andrea Vezzosi, Fernando Peñaranda, Ramón Aguado, Pablo San-Jose, Elsa Prada

Full-shell nanowires have been proposed as an alternative nanowire design in the search of topological superconductivity and Majorana zero modes (MZMs). They are hybrid nanostructures consisting of a semiconductor core fully covered by a thin superconductor shell and subject to a magnetic flux. In this work we critically examine this proposal, finding a very rich spectral phenomenology that combines the Little-Parks modulation of the parent-gap superconductor with flux, the presence of flux-dispersing Caroli-de Gennes-Matricon (CdGM) analog subgap states, and the emergence of MZMs across finite flux intervals that depend on the transverse wavefunction profile of the charge density in the core section. Through microscopic simulations and analytical derivations, we study different regimes for the semiconductor core, ranging from the hollow-core approximation, to the tubular-core nanowire appropriate for a semiconductor tube with an insulating core, to the solid-core nanowire. We compute the phase diagrams for the different models in cylindrical nanowires and find that MZMs typically coexist with CdGM analogs at zero energy, rendering them gapless. However, we also find topologically protected parameter regions, or islands, with gapped MZMs. In this sense, the most promising candidate to obtain topologically protected MZMs in a full-shell geometry is the nanowire with a tubular-shaped core. Moving beyond pristine nanowires, we study the effect of mode mixing perturbations. Strikingly, mode mixing can act like a topological $p$-wave pairing between particle-hole Bogoliubov partners, and is therefore able to create new topologically protected MZMs in regions of the phase diagram that were originally trivial. As a result, the phase diagram is utterly transformed and exhibits protected MZMs in around half of the parameter space.


The Nordic-walking mechanism and its explanation of deconfined pseudocriticality from Wess-Zumino-Witten theory. (arXiv:2312.11614v1 [cond-mat.str-el])
Bilal Hawashin, Astrid Eichhorn, Lukas Janssen, Michael M. Scherer, Shouryya Ray

The understanding of phenomena falling outside the Ginzburg-Landau paradigm of phase transitions represents a key challenge in condensed matter physics. A famous class of examples is constituted by the putative deconfined quantum critical points between two symmetry-broken phases in layered quantum magnets, such as pressurised SrCu$_2$(BO$_3$)$_2$. Experiments find a weak first-order transition, which simulations of relevant microscopic models can reproduce. The origin of this behaviour has been a matter of considerable debate for several years. In this work, we demonstrate that the nature of the deconfined quantum critical point can be best understood in terms of a novel dynamical mechanism, termed Nordic walking. Nordic walking denotes a renormalisation group flow arising from a beta function that is flat over a range of couplings. This gives rise to a logarithmic flow that is faster than the well-known walking behaviour, associated with the annihilation and complexification of fixed points, but still significantly slower than the generic running of couplings. The Nordic-walking mechanism can thus explain weak first-order transitions, but may also play a role in high-energy physics, where it could solve hierarchy problems.

We analyse the Wess-Zumino-Witten field theory pertinent to deconfined quantum critical points with a topological term in 2+1 dimensions. To this end, we construct an advanced functional renormalisation group approach based on higher-order regulators. We thereby calculate the beta function directly in 2+1 dimensions and provide evidence for Nordic walking.


Universal structure of measurement-induced information in many-body ground states. (arXiv:2312.11615v1 [quant-ph])
Zihan Cheng, Rui Wen, Sarang Gopalakrishnan, Romain Vasseur, Andrew C. Potter

Unlike unitary dynamics, measurements of a subsystem can induce long-range entanglement via quantum teleportation. The amount of measurement-induced entanglement or mutual information depends jointly on the measurement basis and the entanglement structure of the state (before measurement), and has operational significance for whether the state is a resource for measurement-based quantum computing, as well as for the computational complexity of simulating the state using quantum or classical computers. In this work, we examine entropic measures of measurement-induced entanglement (MIE) and information (MII) for the ground-states of quantum many-body systems in one- and two- spatial dimensions. From numerical and analytic analysis of a variety of models encompassing critical points, quantum Hall states, string-net topological orders, and Fermi liquids, we identify universal features of the long-distance structure of MIE and MII that depend only on the underlying phase or critical universality class of the state. We argue that, whereas in $1d$ the leading contributions to long-range MIE and MII are universal, in $2d$, the existence of a teleportation transition for finite-depth circuits implies that trivial $2d$ states can exhibit long-range MIE, and the universal features lie in sub-leading corrections. We introduce modified MIE measures that directly extract these universal contributions. As a corollary, we show that the leading contributions to strange-correlators, used to numerically identify topological phases, are in fact non-universal in two or more dimensions, and explain how our modified constructions enable one to isolate universal components. We discuss the implications of these results for classical- and quantum- computational simulation of quantum materials.


Moir\'e Fractional Chern Insulators III: Hartree-Fock Phase Diagram, Magic Angle Regime for Chern Insulator States, the Role of the Moir\'e Potential and Goldstone Gaps in Rhombohedral Graphene Superlattices. (arXiv:2312.11617v1 [cond-mat.str-el])
Yves H. Kwan, Jiabin Yu, Jonah Herzog-Arbeitman, Dmitri K. Efetov, Nicolas Regnault, B. Andrei Bernevig

We investigate in detail the $\nu=+1$ displacement-field-tuned interacting phase diagram of $L=3,4,5,6,7$ layer rhombohedral graphene aligned to hBN (R$L$G/hBN). Our calculations account for the 3D nature of the Coulomb interaction, the inequivalent stacking orientations $\xi=0,1$, the effects of the filled valence bands, and the choice of `interaction scheme' for specifying the many-body Hamiltonian. We show that the latter has a dramatic impact on the Hartree-Fock phase boundaries and the properties of the phases, including for pentalayers (R5G/hBN) with large displacement field $D$ where recent experiments observed a Chern insulator at $\nu=+1$ and fractional Chern insulators for $\nu<1$. In this large $D$ regime, the low-energy conduction bands are polarized away from the aligned hBN layer, and are hence well-described by the folded bands of moir\'eless rhombohedral graphene at the non-interacting level. Despite this, the filled valence bands develop moir\'e-periodic charge density variations which can generate an effective moir\'e potential, thereby explicitly breaking the approximate continuous translation symmetry in the conduction bands, and leading to contrasting electronic topology in the ground state for the two stacking arrangements. Within time-dependent Hartree-Fock theory, we further characterize the strength of the moir\'e pinning potential in the Chern insulator phase by computing the low-energy $\mathbf{q}=0$ collective mode spectrum, where we identify competing gapped pseudophonon and valley magnon excitations. Our results emphasize the importance of careful examination of both the single-particle and interaction model for a proper understanding of the correlated phases in R$L$G/hBN.


Direct observation of a magnetic field-induced Wigner crystal. (arXiv:2312.11632v1 [cond-mat.mes-hall])
Yen-Chen Tsui, Minhao He, Yuwen Hu, Ethan Lake, Taige Wang, Kenji Watanabe, Takashi Taniguchi, Michael P. Zaletel, Ali Yazdani

Eugene Wigner predicted long ago that when the Coulomb interactions between electrons become much stronger than their kinetic energy, electrons crystallize into a closely packed lattice. A variety of two-dimensional systems have shown evidence for Wigner crystals; however, a spontaneously formed classical or quantum Wigner crystal (WC) has never been directly visualized. Neither the identification of the WC symmetry nor direct investigation of its melting has been accomplished. Here we use high-resolution scanning tunneling microscopy (STM) measurements to directly image a magnetic field-induced electron WC in Bernal-stacked bilayer graphene (BLG), and examine its structural properties as a function of electron density, magnetic field, and temperature. At high fields and the lowest temperature, we observe a triangular lattice electron WC in the lowest Landau Level (LLL) of BLG. The WC possesses the expected lattice constant and is robust in a range of filling factors between $\nu\sim$ 0.13 and $\nu\sim$ 0.38 except near fillings where it competes with fractional quantum Hall (FQH) states. Increasing the density or temperature results in the melting of the WC into a liquid phase that is isotropic but has a modulated structure characterized by the WC's Bragg wavevector. At low magnetic fields, the WC unexpectedly transitions into an anisotropic stripe phase, which has been commonly anticipated to form in higher LLs. Analysis of individual lattice sites reveals signatures that may be related to the quantum zero-point motion of electrons in the WC lattice.


Layer Hall counterflow as a model probe of magic-angle twisted bilayer graphene. (arXiv:2312.11662v1 [cond-mat.mes-hall])
Jihang Zhu, Dawei Zhai, Cong Xiao, Wang Yao

The recent constructions of flat moir\'e minibands in specifically twisted multilayer graphene and twisted transition metal dichalcogenides (TMDs) have facilitated the observation of strong correlations with a convenient tunability. These correlations in flat bands result in the band dispersion heavily influenced by carrier densities, leading to filling-dependent quasiparticle band renormalizations. Particularly, in magic-angle twisted bilayer graphene (MATBG), the band structure--including the quasiparticle energy and wavefunction--is crucial in understanding the correlated properties. Previous theoretical studies have demonstrated the presence of a time-reversal-even charge Hall counterflow in response to a direct current (DC) electric field in twisted bilayers as chiral structures. In this study, we show that such layer Hall counterflow can serve as a sensitive probe for MATBG model parameters, which are currently ambiguous as a result of unavoidable structural relaxation and twist-angle disorder. We present the layer Hall counterflow and the associated in-plane magnetization for three different MATBG continuum models, based on which many-body interacting models have been widely applied to study strong correlations in MATBG. At the single-particle level, our findings indicate notable differences in layer-projected Hall conductivity, both in magnitude and sign, between different MATBG continuum models. Furthermore, our self-consistent Hartree calculations, performed on each of these single-particle continuum models, reveal renormalized layer-projected Hall conductivity by the self-consistent Hartree field.


Dynamical Mean Field Theory for Low Density and Dirac Materials. (arXiv:2312.11693v1 [cond-mat.str-el])
Anqi Mu, Zhiyuan Sun, Andrew J. Millis

The qualitative reliability of the dynamical mean field theory (DMFT) is investigated for systems in which either the actual carrier density or the effective carrier density is low, by comparing the exact perturbative and dynamical mean field expressions of electron scattering rates and optical conductivities. We study two interacting systems: tight binding models in which the chemical potential is near a band edge and Dirac systems in which the chemical potential is near the Dirac point. In both systems it is found that DMFT underestimates the low frequency, near-Fermi surface single particle scattering rate by a factor proportional to the particle density. The quasiparticle effective mass is qualitatively incorrect for the low density tight binding model but not necessarily for Dirac systems. The dissipative part of the optical conductivity is more subtle: in the exact calculation vertex corrections, typically neglected in DMFT calculations, suppress the low frequency optical absorption, compensating for some of the DMFT underestimate of the scattering rate. The role of vertex corrections in calculating the conductivity for Dirac systems is clarified and a systematic discussion is given of the approach to the Galilean/Lorentz invariant low density limit. Relevance to recent calculations related to Weyl metals is discussed.


Gate-defined superconducting channel in magic-angle twisted bilayer graphene. (arXiv:2312.11698v1 [cond-mat.mes-hall])
Giulia Zheng, Elías Portolés, Alexandra Mestre-Torá, Marta Perego, Takashi Taniguchi, Kenji Watanabe, Peter Rickhaus, Folkert K. de Vries, Thomas Ihn, Klaus Ensslin, Shuichi Iwakiri

Magic-angle twisted bilayer graphene (MATBG) combines in one single material different phases like insulating, metallic and superconducting. These phases and their in-situ tunability make MATBG an important platform for the fabrication of superconducting devices. We realize a split gate-defined geometry which enables us to tune the width of a superconducting channel formed in MATBG. We observe a smooth transition from superconductivity to highly resistive transport by progressively reducing the channel width using the split gates or by reducing the density in the channel. Using the gate-defined constriction, we control the flow of the supercurrent, either guiding it through the constriction or throughout the whole device or even blocking its passage completely. This serves as a foundation for developing quantum constriction devices like superconducting quantum point contacts, quantum dots, and Cooper-pair boxes in MATBG.


From Dry to Wet Vertex Model Dynamics: Generating Sustained Flows. (arXiv:2312.11756v1 [cond-mat.soft])
Jan Rozman, Chaithanya K. V. S., Julia M. Yeomans, Rastko Sknepnek

Complex tissue flows in epithelia are driven by intra- and inter-cellular processes that generate, maintain, and coordinate mechanical forces. There has been growing evidence that cell shape anisotropy, manifested as nematic order, plays an important role in this process. Here we extend a nematic vertex model by replacing substrate friction with internal viscous dissipation, of relevance to epithelia not supported by a substrate or the extracellular matrix, such as many early-stage embryos. When coupled to cell shape anisotropy, the internal viscous dissipation allows for long-range velocity correlations and thus enables the spontaneous emergence of flows with a large degree of spatiotemporal organisation. We demonstrate sustained flow in epithelial sheets confined to a channel, thus providing a link between the dynamical behaviour of continuum active nematics and the cell-level vertex model of tissue dynamics.


Twisted van der Waals Quantum Materials: Fundamentals, Tunability and Applications. (arXiv:2312.11757v1 [cond-mat.mtrl-sci])
Xueqian Sun, Manuka Suriyage, Ahmed Khan, Mingyuan Gao, Jie Zhao, Boqing Liu, Mehedi Hasan, Sharidya Rahman, Ruosi Chen, Ping Koy Lam, Yuerui Lu

Twisted vdW quantum materials have emerged as a rapidly developing field of 2D semiconductors. These materials establish a new central research area and provide a promising platform for studying quantum phenomena and investigating the engineering of novel optoelectronic properties such as single-photon emission, non-linear optical response, magnon physics, and topological superconductivity. These captivating electronic and optical properties result from, and can be tailored by, the interlayer coupling using moir\'e patterns formed by vertically stacking atomic layers with controlled angle misorientation or lattice mismatch. Their outstanding properties and the high degree of tunability position them as compelling building blocks for both compact quantum-enabled devices and classical optoelectronics. This article offers a comprehensive review of recent advancements in the understanding and manipulation of twisted van der Waals structures and presents a survey of the state-of-the-art research on moir\'e superlattices, encompassing interdisciplinary interests. It delves into fundamental theories, synthesis and fabrication, and visualization techniques, and the wide range of novel physical phenomena exhibited by these structures, with a focus on their potential for practical device integration in applications ranging from quantum information to biosensors, and including classical optoelectronics such as modulators, light emitting diodes (LEDs), lasers, and photodetectors. It highlights the unique ability of moir\'e superlattices to connect multiple disciplines, covering chemistry, electronics, optics, photonics, magnetism, topological and quantum physics. This comprehensive review provides a valuable resource for researchers interested in moir\'e superlattices, shedding light on their fundamental characteristics and their potential for transformative applications in various fields.


Feature-energy duality of topological boundary states in multilayer quantum spin Hall insulator. (arXiv:2312.11794v1 [cond-mat.mtrl-sci])
Yueh-Ting Yao, Xiaoting Zhou, Yi-Chun Hung, Hsin Lin, Arun Bansil, Tay-Rong Chang

Gapless topological boundary states characterize nontrivial topological phases arising from the bulk-boundary correspondence in symmetry-protected topological materials, such as the emergence of helical edge states in a two-dimensional $\mathbb{Z}_2$ topological insulator. However, the incorporation of symmetry-breaking perturbation terms in the Hamiltonian leads to the gapping of these edge bands, resulting in missing these crucial topological boundary states. In this work, we systematically investigate the robustness of bulk-boundary correspondence in the quantum spin Hall insulator via recently introduced feature spectrum topology. Our findings present a comprehensive understanding of feature-energy duality, illustrating that the aggregate number of gapless edge states in the energy-momentum ($\it{E-k}$) map and the non-trivial edge states in the $\hat{S}_z$ feature spectrum equals the spin Chern number of multilayer quantum spin Hall insulator. We identify a van der Waals material bismuth bromide $\rm(Bi_4Br_4)$ as a promising candidate through first-principles calculations. Our work not only unravels the intricacies of bulk-boundary correspondence but also charts a course for exploring quantum spin Hall insulators with high spin-Chern number.


On-Surface Synthesis of Silole and Disilacyclooctaene Derivatives. (arXiv:2312.11959v1 [cond-mat.mtrl-sci])
Kewei Sun, Lauri Kurki, Orlando J. Silveira, Tomohiko Nishiuchi, Takashi Kubo, Ondřej Krejčí, Adam S. Foster, Shigeki Kawai

Sila-cyclic rings are a class of organosilicon cyclic compounds and have abundant application in organic chemistry and materials science. However, it is still challenging to synthesize compounds with sila-cyclic rings in solution chemistry due to their low solubility and high reactivity. Recently, on-surface synthesis was introduced into organosilicon chemistry as 1,4- disilabenzene bridged nanostructures were obtained via coupling between bromo-substituted molecules and silicon atoms on Au(111). Here, we extend this strategy for syntheses of silole derivatives and graphene nanoribbons with eight-membered sila-cyclic rings from 2,2',6,6'- tetrabromobiphenyl and 1,4,5,8-tetrabromonaphthalene on Au(111), respectively. Their structures and electronic properties were investigated by a combination of scanning tunneling microscopy/spectroscopy and density functional theory calculations. This work demonstrates a generality of this synthesis strategy to fabricate various silicon incorporated nanostructures.


Origin of chirality in transition-metal dichalcogenides. (arXiv:2312.11979v1 [cond-mat.str-el])
Kwangrae Kim, Hyun-Woo J. Kim, Seunghyeok Ha, Hoon Kim, Jin-Kwang Kim, Jaehwon Kim, Hyunsung Kim, Junyoung Kwon, Jihoon Seol, Saegyeol Jung, Changyoung Kim, Ahmet Alatas, Ayman Said, Michael Merz, Matthieu Le Tacon, Jin Mo Bok, Ki-Seok Kim, B. J. Kim

Chirality is a ubiquitous phenomenon in which a symmetry between left- and right-handed objects is broken, examples in nature ranging from subatomic particles and molecules to living organisms. In particle physics, the weak force is responsible for the symmetry breaking and parity violation in beta decay, but in condensed matter systems interactions that lead to chirality remain poorly understood. Here, we unravel the mechanism of chiral charge density wave formation in the transition-metal dichalcogenide 1T-TiSe2. Using representation analysis, we show that charge density modulations and ionic displacements, which transform as a continuous scalar field and a vector field on a discrete lattice, respectively, follow different irreducible representations of the space group, despite the fact that they propagate with the same wave-vectors and are strongly coupled to each other. This charge-lattice symmetry frustration is resolved by further breaking of all symmetries not common to both sectors through induced lattice distortions, thus leading to chirality. Our theory is verified using Raman spectroscopy and inelastic x-ray scattering, which reveal that all but translation symmetries are broken at a level not resolved by state-of-the-art diffraction techniques.


GdAlSi: An antiferromagnetic topological Weyl semimetal with non-relativistic spin splitting. (arXiv:2312.11980v1 [cond-mat.str-el])
Jadupati Nag, Bishal Das, Sayantika Bhowal, Yukimi Nishioka, Barnabha Bandyopadhyay, Shiv Kumar, Kenta Kuroda, Akio Kimura, K. G. Suresh, Aftab Alam

Spintronics has emerged as a viable alternative to traditional electronics based technologies in the past few decades. While on one hand, the discovery of topological phases of matter with protected spin-polarized states has opened up exciting prospects, recent revelation of intriguing non-relativistic spin splitting in collinear antiferromagnetic materials with unique symmetries facilitate a wide possibility of realizing both these features simultaneously. In this work, we report the co-existence of these two intriguing properties within a single material: GdAlSi. It crystallizes in a body-centered tetragonal structure with a non-centrosymmetric space group $I4_{1}md$ ($109$). The magnetization data indicates antiferromagnetic ordering with an ordering temperature ($T_N$) 32 K. Ab-initio calculations reveal GdAlSi to be a collinear antiferromagnetic Weyl semimetal with an unconventional, momentum-dependent spin splitting, also referred to as altermagnet. Angle-resolved photoemission spectroscopy measurements on GdAlSi single crystals subsequently confirm the presence of Fermi arcs, a distinctive hallmark of Weyl semimetals. Electric and magnetic multipole analysis provides a deeper understanding of the symmetry-mediated, momentum-dependent spin splitting, which has strictly non-relativistic origin. To the best of our knowledge, such co-existence of unconventional antiferromagnetic order and non-trivial topology is unprecedented and has never been observed before in a single material, rendering GdAlSi a special and promising candidate material. We propose a device harnessing these features, poised to enable practical and efficient topotronic applications.


Quasiperiodic gallium adlayer on i-Al-Pd-Mn. (arXiv:2312.12005v1 [cond-mat.mtrl-sci])
Pramod Bhakuni, Marian Krajčí, Sudipta Roy Barman

Using scanning tunneling microscopy (STM), low energy electron diffraction (LEED), and density functional theory (DFT), we demonstrate the formation of quasicrystalline gallium adlayer on icosahedral ($i$)-Al-Pd-Mn. Quasiperiodic motifs are evident in the STM topography images, including the Ga white flower (GaWF) and $\tau$ inflated GaWF ($\tau$-GaWF), where $\tau$ is the golden mean. A larger and more complicated ring motif is also identified, comprised of a bright center and an outer ring of pentagons. The fast Fourier transform of the STM images exhibits distinct quasiperiodic spots, thereby establishing quasiperiodicity on a length scale of $\sim$350 nm. Based on our DFT calculations, the preferred adsorption sites of Ga on i-Al-Pd-Mn are determined to be either the Mn atoms at the center of the Penrose P1 tile or the vertices of the P1 tile containing Pd atoms at the center of a cluster of 5 Al atoms (5-Al). The GaWF motif is modeled by an inner 6 atom Ga cluster (6-Ga) around the central Mn atom and an outer ring of 5 Ga atoms adsorbed at the centers of the 5-Al clusters, both having pentagonal symmetry. The $\tau$-GaWF motif is modeled by the 6-Ga arranged on the $\tau$-P1 tiling, while the ring motif is modeled by Ga atoms adsorbed at the center of 5-Al clusters above a Pd atom. The side lengths and diameters of the GaWF, $\tau$-GaWF, and the ring motifs are $\tau$ scaled and show excellent agreement with the DFT-based models. An additional indication of the quasiperiodic characteristics of the Ga monolayer is the 5-fold LEED patterns that were detected throughout the entire range of beam energy that was measured.


Quantum field theories of relativistic Luttinger fermions. (arXiv:2312.12058v1 [hep-th])
Holger Gies, Philip Heinzel, Johannes Laufkötter, Marta Picciau

We propose relativistic Luttinger fermions as a new ingredient for the construction of fundamental quantum field theories. We construct the corresponding Clifford algebra and the spin metric for relativistic invariance of the action using the spin-base invariant formalism. The corresponding minimal spinor has 32 complex components, matching with the degrees of freedom of a standard-model generation including a right-handed neutrino. The resulting fermion fields exhibit a canonical scaling different from Dirac fermions and thus support the construction of novel relativistic and perturbatively renormalizable, interacting quantum field theories. In particular, new asymptotically free self-interacting field theories can be constructed, representing first examples of high-energy complete quantum field theories based on pure matter degrees of freedom. Gauge theories with relativistic Luttinger fermions exhibit a strong paramagnetic dominance, requiring large nonabelian gauge groups to maintain asymptotic freedom. We comment on the possibility to use Luttinger fermions for particle physics model building and the expected naturalness properties of such models.


Spin-dependent localization of helical edge states in a non-Hermitian phononic crystal. (arXiv:2312.12060v1 [cond-mat.mes-hall])
Junpeng Wu, Riyi Zheng, Jialuo Liang, Manzhu Ke, Jiuyang Lu, Weiyin Deng, Xueqin Huang, Zhengyou Liu

As a distinctive feature unique to non-Hermitian systems, non-Hermitian skin effect displays fruitful exotic phenomena in one or higher dimensions, especially when conventional topological phases are involved. Among them, hybrid skin-topological effect is theoretically proposed recently, which exhibits anomalous localization of topological boundary states at lower-dimensional boundaries accompanied by extended bulk states. Here we experimentally realize the hybrid skin-topological effect in a non-Hermitian phononic crystal. The phononic crystal, before tuning to be non-Hermitian, is an ideal acoustic realization of the Kane-Mele model, which hosts gapless helical edge states at the boundaries. By introducing a staggered distribution of loss, the spin-dependent edge modes pile up to opposite corners, leading to a direct observation of the spin-dependent hybrid skin-topological effect. Our work highlights the interplay between topology and non-Hermiticity and opens new routes to non-Hermitian wave manipulations.


Bulk-boundary correspondence in topological systems with the momentum dependent energy shift. (arXiv:2312.12127v1 [cond-mat.quant-gas])
Huan-Yu Wang, Zhen-Biao Yang, Wu-Ming Liu

Bulk-boundary correspondences (BBCs) remain the central topic in modern condensed matter physics, and are gaining increasing interests with the recent discovery of non-Hermitian skin effects. However, there still exist profound features of BBCs that are beyond the existing framework. Here, we report the unexpected behavior of BBC when the Hamiltonian contains term of the form $d_0(k) I$, which serves as a momentum dependent energy shift. For Hermitian cases, momentum dependent energy shift can force the system to be semimetal, where topological phase transitions can take place with the upper and the lower bands keeping untouched. The proper modified BBC should be reconstructed from the perspective of the direct band gap. In non-Hermitian cases, skin effects are found to be capable of coexisting with the preserved BBC, of which the process can be greatly facilitated by the complex $d_0(k)I$. Remarkably, such results can be led a further step and contrary to the intuitive consideration, the modified BBC in Hermitian systems can be restored to be conventional by including extra non-Hermiticity. The physical origin for these phenomena lies in that $d_0(k)I$ can drastically change the point gap topology. Finally, the corresponding experimental simulations are proposed via the platforms of electric circuits.


Topological spectra and entropy of chromatin loop networks. (arXiv:2312.12159v1 [physics.bio-ph])
Andrea Bonato, Dom Corbett, Sergey Kitaev, Davide Marenduzzo, Alexander Morozov, Enzo Orlandini

The 3D folding of a mammalian gene can be studied by a polymer model, where the chromatin fibre is represented by a semiflexible polymer which interacts with multivalent proteins, representing complexes of DNA-binding transcription factors and RNA polymerases. This physical model leads to the natural emergence of clusters of proteins and binding sites, accompanied by the folding of chromatin into a set of topologies, each associated with a different network of loops. Here we combine numerics and analytics to first classify these networks and then find their relative importance or statistical weight, when the properties of the underlying polymer are those relevant to chromatin. Unlike polymer networks previously studied, our chromatin networks have finite average distances between successive binding sites, and this leads to giant differences between the weights of topologies with the same number of edges and nodes but different wiring. These weights strongly favour rosette-like structures with a local cloud of loops with respect to more complicated non-local topologies. Our results suggest that genes should overwhelmingly fold into a small fraction of all possible 3D topologies, which can be robustly characterised by the framework we propose here.


Microscopic theory of current-induced skyrmion transport and its application in disordered spin textures. (arXiv:2312.12201v1 [cond-mat.mes-hall])
Emil Östberg, Emil Viñas Boström, Claudio Verdozzi

Magnetic skyrmions hold great promise for realizing compact and stable memory devices that can be manipulated at very low energy costs via electronic current densities. In this work, we extend a recently introduced method to describe classical skyrmion textures coupled to dynamical itinerant electrons. In this scheme, the electron dynamics is described via nonequilibrium Green's functions (NEGF) within the generalized Kadanoff-Baym ansatz, and the classical spins are treated via the Landau-Lifshitz-Gilbert equation. The framework is here extended to open systems, by the introduction of a non-interacting approximation to the collision integral of NEGF. This, in turn, allows us to perform computations of the real-time response of skyrmions to electronic currents in large quantum systems coupled to electronic reservoirs, which exhibit a linear scaling in the number of time steps. We use this approach to investigate how electronic spin currents and dilute spin disorder affects skyrmion transport and the skyrmion Hall drift. Our results show that the skyrmion dynamics is sensitive to the specific form of spin disorder, such that different disorder configurations leads to qualitatively different skyrmion trajectories for the same applied bias. This sensitivity arises from the local spin dynamics around the magnetic impurities, a feature that is expected not to be well captured by phenomenological or spin-only descriptions. At the same time, our findings illustrate the potential of engineering microscopic impurity patterns to steer skyrmion trajectories.


Electrical Activity of Topological Chiral Edge Magnons. (arXiv:2312.12316v1 [cond-mat.mes-hall])
Robin R. Neumann, Jürgen Henk, Ingrid Mertig, Alexander Mook

Topological magnon insulators support chiral edge excitations, whose lack of electric charge makes them notoriously difficult to detect experimentally. We show that relativistic magnetoelectric coupling universally renders chiral edge magnons electrically active, thereby facilitating electrical probes of magnon topology. Considering a two-dimensional out-of-plane magnetized topological magnon insulator, we predict a fluctuation-activated electric polarization perpendicular to the sample edges. Furthermore, the chiral topological electromagnons give rise to a unique in-gap signal in electrical absorption experiments. These results suggest THz spectroscopy as a promising probe for topological magnons.


Energy levels of gapped graphene quantum dots in external fields. (arXiv:2312.12324v1 [cond-mat.mes-hall])
Ahmed Bouhlal, Mohammed El Azar, Ahmed Siari, Ahmed Jellal

We investigate the energy levels of fermions within a circular graphene quantum dot (GQD) subjected to external magnetic and Aharonov-Bohm fields. Solving the eigenvalue equation for two distinct regions allows us to determine the eigenspinors for the valleys $K$ and $K^\prime$. By establishing the continuity of eigenspinors at the GQD interface, we derive an equation that reveals the reliance of energy levels on external physical parameters. Our observations suggest that the symmetry of energy levels hinges on the selected physical parameters. We observe that at low magnetic fields, the energy levels display degeneracy, which diminishes as the field strength increases, coinciding with the convergence of energy levels toward the Landau levels. We illustrate that the introduction of a magnetic flux into the GQD leads to the creation of an energy gap, extending the trapping time of electrons without perturbing the system. Conversely, the addition of gap energy widens the band gap, disrupting the system's symmetry by introducing new energy levels.


Thermal rectification with topological edge states. (arXiv:2312.12374v1 [cond-mat.mes-hall])
Abdulla Alseiari, Michael Hilke

Thermal rectification devices can be important for various thermal management applications. For oscillator chains, thermal rectification was observed when masses are distributed non-uniformly. Leaning on the importance of topological materials, we consider here a simple vibrational topological system, the binary isotope superlattice (BISL). We show that the BISL can be mapped exactly onto the Su-Schrieffer-Heeger (SSH) model, which has different topological phases, including topological edge sates. For the case, where there is a single topological edge state, we show that the BISL exhibits thermal rectification in the presence of a small nonlinear term. Thermal transport is computed using temperature reservoirs connected to both extremities. These results have implications for other classes of topological phonon systems.


Nanocrystal Programmable Assembly Beyond Hard Spheres (or Shapes) and Other (Simple) Potentials. (arXiv:2312.12421v1 [cond-mat.soft])
Alex Travesset

Ligands are the key to almost any strategy in the assembly of programmable nanocrystals (or nanoparticles) and must be accurately considered in any predictive model. Hard Spheres (or Shapes) provide the simplest and yet quite successful approach to assembly, with remarkable sophisticated predictions verified in experiments. There are, however, many situations where hard spheres/shapes predictions fail. This prompts three important questions: {\em In what situations should hard spheres/shapes models be expected to work?} and when they do not work, {\em Is there a general model that successfully corrects hard sphere/shape predictions?} and given other successful models where ligands are included explicitly, and of course, numerical simulations, {\em can we unify hard sphere/shape models, explicit ligand models and all atom simulations?}. The Orbifold Topological Model (OTM) provides a positive answer to these three questions. In this paper, I give a detailed review of OTM, describing the concept of ligand vortices and how it leads to spontaneous valence and nanoparticle ``eigenshapes'' while providing a prediction of the lattice structure, without fitting parameters, which accounts for many body effects not captured in (two-body) potentials. I present a thorough survey of experiments and simulations and show that, to this date, they are in full agreement with the OTM predictions. I will conclude with a discussion on whether NC superlattices are equilibrium structures and some significant challenges in structure prediction.


Edelstein effect induced superconducting diode effect in inversion symmetry breaking MoTe$_2$ Josephson junctions. (arXiv:2303.07701v2 [cond-mat.supr-con] UPDATED)
Pingbo Chen, Gongqi Wang, Bicong Ye, Jinhua Wang, Liang Zhou, Zhenzhong Tang, Le Wang, Jiannong Wang, Wenqing Zhang, Jiawei Mei, Weiqiang Chen, Hongtao He

Superconducting diode effect (SDE) with nonreciprocal supercurrent transport has attracted intense attention recently, not only for its intriguing physics, but also for its great application potential in superconducting circuits. It is revealed in this work that planar Josephson junctions (JJs) based on type-II Weyl semimetal (WSM) MoTe$_2$ can exhibit a prominent SDE due to the emergence of asymmetric Josephson effect (AJE) in perpendicular magnetic fields. The AJE manifests itself in a very large asymmetry in the critical supercurrents with respect to the current direction. The sign of this asymmetry can also be effectively modulated by the external magnetic field. Considering the special noncentrosymmetric crystal symmetry of MoTe$_2$, this AJE is understood in terms of the Edelstein effect, which induces a nontrivial phase shift in the current phase relation of the junctions. Besides these, it is further demonstrated that the rectification of supercurrent in such MoTe$_2$ JJs with the rectification efficiency up to 50.4%, unveiling the great application potential of WSMs in superconducting electronics.


Multiple polaritonic edge states in a Su-Schrieffer-Heeger chain strongly coupled to a multimode cavity. (arXiv:2305.06956v2 [cond-mat.mes-hall] UPDATED)
Thomas F. Allard, Guillaume Weick

A dimerized chain of dipolar emitters strongly coupled to a multimode optical waveguide cavity is studied. By integrating out the photonic degrees of freedom of the cavity, the system is recast in a two-band model with an effective coupling, so that it mimics a variation of the paradigmatic Su-Schrieffer-Heeger model, which features a nontrivial topological phase and hosts topological edge states. In the strong-coupling regime, the cavity photons hybridize the bright dipolar bulk band into a polaritonic one, renormalizing the eigenspectrum and strongly breaking chiral symmetry. This leads to a formal loss of the in-gap edge states present in the topological phase while they merge into the polaritonic bulk band. Interestingly, however, we find that bulk polaritons entering in resonance with the edge states inherit part of their localization properties, so that multiple polaritonic edge states are observed. Although these states are not fully localized on the edges, they present unusual properties. In particular, due to their delocalized bulk part, owing from their polaritonic nature, such edge states exhibit efficient edge-to-edge transport characteristics. Instead of being degenerate, they occupy a large portion of the spectrum, allowing one to probe them in a wide driving frequency range. Moreover, being reminiscent of symmetry-protected topological edge states, they feature a strong tolerance to positional disorder.


Wiedemann-Franz law in graphene in the presence of a weak magnetic field. (arXiv:2307.05477v2 [cond-mat.mes-hall] UPDATED)
Yi-Ting Tu, Sankar Das Sarma

The experimental work [J. Crossno et al., Science 351, 1058 (2016)], which reported the violation of the Wiedemann-Franz law in monolayer graphene characterized by a sharp peak of the Lorenz ratio at a finite temperature, has not been fully explained. Our previous work [Y.-T. Tu and S. Das Sarma, Phys. Rev. B 107, 085401 (2023)] provided a possible explanation through a Boltzmann-transport model with bipolar diffusion and an energy gap possibly induced by the substrate. In this paper, we extend our calculation to include a weak magnetic field perpendicular to the graphene layer, which is experimentally relevant, and may shed light on the possible violation or not of the Wiedemann-Franz law. We find that the magnetic field enhances the size of the peak of the Lorenz ratio but has little effect on its position, and that the transverse component of the Lorenz ratio can be either positive or negative depending on the parameter regime. In addition, we do the same calculation for bilayer graphene in the presence of a magnetic field and show the qualitative similarity with monolayer graphene. Our work should motivate magnetic-field-dependent experiments elucidating the nature of the charge carriers in graphene layers.


Raman spectroscopy of monolayer to bulk PtSe2 exfoliated crystals. (arXiv:2307.15520v4 [cond-mat.mtrl-sci] UPDATED)
Marin Tharrault, Eva Desgué, Dominique Carisetti, Bernard Plaçais, Christophe Voisin, Pierre Legagneux, Emmanuel Baudin

Raman spectroscopy is widely used to assess the quality of 2D materials thin films. This report focuses on $\rm{PtSe_2}$, a noble transition metal dichalcogenide which has the remarkable property to transit from a semi-conductor to a semi-metal with increasing layer number. While polycrystalline $\rm{PtSe_2}$ can be grown with various crystalline qualities, getting insight into the monocrystalline intrinsic properties remains challenging. We report on the study of exfoliated 1 to 10 layers $\rm{PtSe_2}$ by Raman spectroscopy, featuring record linewidth. The clear Raman signatures allow layer-thickness identification and provides a reference metrics to assess crystal quality of grown films.


Anomalous Coherence Length in Superconductors with Quantum Metric. (arXiv:2308.05686v3 [cond-mat.supr-con] UPDATED)
Jin-Xin Hu, Shuai A. Chen, K. T. Law

The coherence length $\xi$ is a fundamental length scale of superconductors which governs the sizes of Cooper pairs, vortices, Andreev bound states and more. In existing microscopic theories of superconductivity, it is expected that as the attractive interaction increases, $\xi$ decreases as the electrons are bound together more strongly. In BCS theory, for example, the coherence length is $\xi_\mathrm{BCS} = \hbar v_{F}/\Delta$, where $v_{F}$ is the Fermi velocity and $\Delta$ is the pairing gap. It is clear that increasing $\Delta$ will shorten $\xi_\mathrm{BCS}$. However, the situation is puzzling for superconductors with completely flat bands in which $v_{F}$ goes to zero and $\xi_\mathrm{BCS}$ is expected to be zero. In this work, we show that the quantum metric, which is the real part of the quantum geometric tensor, gives rise to an anomalous contribution to the coherence length. Specifically, $\xi = \sqrt{\xi_\mathrm{BCS}^2 +\ell_{\mathrm{qm}}^{2}}$ for a superconductor where $\ell_{\mathrm{qm}}$ is the quantum metric contribution. In the flat band limit, $\xi$ does not vanish but bound by $\ell_{\mathrm{qm}}$. Incredibly, for the nontrivial flat bands with Chern number $C$, $\xi$ has a topological bound of $\xi\geq a\sqrt{\vert C \vert/4\pi}$ where $a$ is the lattice constant. Physically, the Cooper pair size of a superconductor cannot be squeezed down to a size smaller than $\ell_{\mathrm{qm}}$ which is a fundamental length scale determined by the quantum geometry of the bands. Finally, we calculate the quantum metric contributions for the superconducting moir\'e graphene family and show that the quantum metric effects are very important in these superconductors.


Quarter-Metal Phases in Multilayer Graphene: Ising-XY and Annular Lifshitz Transitions. (arXiv:2310.10759v2 [cond-mat.mes-hall] UPDATED)
Mainak Das, Chunli Huang

Recent experiments have uncovered a distinctive magnetic metal in lightly-doped multilayer graphene, coined the \textit{quarter metal}. This quarter metal consolidates all the doped carriers, originally distributed evenly across the four (or twelve) Fermi surfaces of the paramagnetic state, into one expansive Fermi surface by breaking time-reversal and/or inversion symmetry. In this work, we map out a comprehensive mean-field phase diagram of the quarter-metal in rhombohedral trilayer graphene within the four dimensional parameter space spanned by the density $n_e$, interlayer electric potential $U$, external magnetic field parallel to the two-dimensional material plane $B_{\parallel}$ and Kane-Mele spin-orbit coupling $\lambda$. We found an annular Lifshitz phase transition and a Ising-XY phase transition and locate these phase boundaries on the experimental phase diagram. The movement of the Ising-XY phase boundary offers insights into $\lambda$. Our analysis reveals that it moves along the line $\partial n_e/\partial B_{\parallel} \sim -0.5\times 10^{11} \text{cm}^{-2}\text{T}^{-1}$ within the $n_e$-$B_{\parallel}$ parameter space when $\lambda=30\mu$eV. Additionally, we estimated the in-plane spin susceptibility of the valley-Ising quarter-metal $\chi_{_\parallel}\sim 8~\mu\text{eV} ~\text{T}^{-2}$. Beyond these quantitative findings, two general principles emerge from our study: 1) The valley-XY quarter metal's dominance in the $n_e-U$ parameter space grows with an increasing number of layers due to the reduce valley polarization variations within the Fermi sea. 2) Layer polarization near the band edge plays an important role in aiding the re-entrance of the paramagnetic state at low density. The insights derived from the quarter metal physics may shed light on the complex behaviors observed in other regions of the phase diagram.


Flat band effects on the ground-state BCS-BEC crossover in atomic Fermi gases in a quasi-two-dimensional Lieb lattice. (arXiv:2310.12944v2 [cond-mat.quant-gas] UPDATED)
Hao Deng, Chuping Li, Yuxuan Wu, Lin Sun, Qijin Chen

The ground-state superfluid behavior of ultracold atomic Fermi gases with an on-site attractive interaction in a quasi-two-dimensional Lieb lattice is studied using BCS mean-field theory, within the context of BCS-BEC crossover. We find that the flat band leads to nontrivial exotic effects. As the Fermi level enters the flat band, both the pairing gap and the in-plane superfluid density exhibit an unusual power law as a function of interaction, with strongly enhanced quantum geometric effects, in addition to a dramatic increase of compressibility as the interaction approaches the BCS limit. As the Fermi level crosses the van Hove singularities, the character of pairing changes from particle-like to hole-like or vice versa. We present the computed phase diagram, in which a pair density wave state emerges at high densities with relatively strong interaction strength.


$O(N)$ smectic $\sigma$-model. (arXiv:2310.13046v2 [cond-mat.stat-mech] UPDATED)
Tzu-Chi Hsieh, Leo Radzihovsky

A unidirectional "density" wave order in an otherwise isotropic environment is guaranteed to display a smecticlike Goldstone mode. Examples of such "soft" states include conventional smectic liquid crystals, putative Fulde-Ferrell-Larkin-Ovchinnikov superfluids, and helical states of frustrated bosons and spins. Here we develop generalized spin-smectic $\sigma$-models that break $O(N)$ internal symmetry in addition to the $d$-dimensional rotational and uniaxial translational symmetries. We explore long-wavelength properties of such strongly fluctuating states, show that they are characterized by a "double-power-law" static structure peak, and analyze their asymptotic symmetry-reduced crossover to conventional low-energy modes. We also present the associated Ginzburg-Landau theory, describing phase transition into such spin-smectic states, and discuss experimental realization of such models.


Topological Orders Beyond Topological Quantum Field Theories. (arXiv:2311.03353v2 [cond-mat.mes-hall] UPDATED)
P. Vojta, G. Ortiz, Z. Nussinov

Systems displaying quantum topological order feature robust characteristics that are very attractive to quantum computing schemes. Topological quantum field theories have proven to be powerful in capturing the quintessential attributes of systems displaying topological order including, in particular, their anyon excitations. Here, we investigate systems that lie outside this common purview, and present a rich class of models exhibiting topological orders with distance-dependent interacting anyons. As we illustrate, in some instances, the gapped lowest-energy excitations are comprised of anyons that densely cover the entire system. This leads to behaviors not typically described by topological quantum field theories. We examine these models by performing dualities to systems displaying conventional (i.e., Landau) orders. Our approach enables a general method for mapping generic Landau-type theories to dual models with topological order of the same spatial dimension. The low-energy subspaces of our models can be made more resilient to thermal effects than those of surface codes.


Polarization-induced Weyl phonons in nonsymmorphic crystals. (arXiv:2312.07493v2 [cond-mat.mes-hall] UPDATED)
Sahal Kaushik

In this work, it is shown that in certain nonsymmorphic space groups, electric polarization due to an external electric field or ferroelectric order produces Weyl phonons.


Smart sensing of the multifunctional properties of magnetron sputtered $MoS_2$ across the amorphous-crystalline transition. (arXiv:2312.10180v2 [cond-mat.mtrl-sci] UPDATED)
Jose L. Ocana-Pujol, Rebecca A. Gallivan, Ramon Camilo Dominguez Ordoñez, Nikolaus Porenta, Arnold Müller, Christof Vockenhuber, Ralph Spolenak, Henning Galinski

Molybdenum disulfide, $MoS_2$, is a next-generation semiconductor and is frequently integrated into emergent optoelectronic technologies based on two-dimensional materials. Here, we present a method that provides direct optical feedback on the thickness and crystallinity of sputter-deposited $MoS_2$ down to the few-layer regime. This smart sensing enables tracking the material's functional properties, such as excitonic response, sheet resistance, and hardness across the amorphous-crystalline transition. To illustrate the potential of such feedback-controlled fabrication, we realized $MoS_2$-based hyperbolic metamaterials (HMM) with controllable optical topological transitions and hardness.


Superconductivity in a ferroelectric-like topological semimetal SrAuBi. (arXiv:2312.10354v2 [cond-mat.supr-con] UPDATED)
Hidefumi Takahashi, Tomohiro Sasaki, Akitoshi Nakano, Kazuto Akiba, Masayuki Takahashi, Alex H. Mayo, Masaho Onose, Tatsuo C. Kobayashi, Shintaro Ishiwata

Given the rarity of metallic systems that exhibit ferroelectric-like transitions, it is apparently challenging to find a system that simultaneously possesses superconductivity and ferroelectric-like structural instability. Here, we report the observation of superconductivity at 2.4 K in a layered semimetal SrAuBi characterized by strong spin-orbit coupling (SOC) and ferroelectric-like lattice distortion. Single crystals of SrAuBi have been successfully synthesized and found to show a polar-nonpolar structure transition at 214 K, which is associated with the buckling of Au-Bi honeycomb lattice. On the basis of the band calculations considering SOC, we found significant Rashba-type spin splitting and symmetry-protected multiple Dirac points near the Fermi level. We believe that this discovery opens up new possibilities of pursuing exotic superconducting states associated with the semimetallic band structure without space inversion symmetry and the topological surface state with the strong SOC.


Found 7 papers in prb
Date of feed: Wed, 20 Dec 2023 04:16:55 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)

Topological zero modes and edge symmetries of metastable Markovian bosonic systems
Vincent P. Flynn, Emilio Cobanera, and Lorenza Viola
Author(s): Vincent P. Flynn, Emilio Cobanera, and Lorenza Viola

Tight bosonic analogs of free-fermionic symmetry-protected topological phases, and their associated edge-localized excitations, have long evaded the grasp of condensed-matter and AMO physics. In this paper, building on our initial exploration [Phys. Rev. Lett. 127, 245701 (2021)], we identify a broa…


[Phys. Rev. B 108, 214312] Published Tue Dec 19, 2023

Topological superconductivity mediated by magnons of helical magnetic states
Kristian Mæland, Sara Abnar, Jacob Benestad, and Asle Sudbø
Author(s): Kristian Mæland, Sara Abnar, Jacob Benestad, and Asle Sudbø

We recently showed that spin fluctuations of noncoplanar magnetic states can induce topological superconductivity in an adjacent normal metal [Mæland et al., Phys. Rev. Lett. 130, 156002 (2023)]. The noncolinear nature of the spins was found to be essential for this result, while the necessity of n…


[Phys. Rev. B 108, 224515] Published Tue Dec 19, 2023

Weak antilocalization in the transition metal telluride ${\mathrm{Ta}}_{2}{\mathrm{Pd}}_{3}{\mathrm{Te}}_{5}$
Wen-He Jiao, Hang-Qiang Qiu, Wuzhang Yang, Jin-Ke Bao, Shaozhu Xiao, Yi Liu, Yuke Li, Guang-Han Cao, Xiaofeng Xu, Zhi Ren, and Peng Zhang
Author(s): Wen-He Jiao, Hang-Qiang Qiu, Wuzhang Yang, Jin-Ke Bao, Shaozhu Xiao, Yi Liu, Yuke Li, Guang-Han Cao, Xiaofeng Xu, Zhi Ren, and Peng Zhang

We report transport studies on the layered van der Waals topological crystalline insulator ${\mathrm{Ta}}_{2}{\mathrm{Pd}}_{3}{\mathrm{Te}}_{5}$. The temperature-dependent resistance at high temperature is dominated by a bulk insulating gap and tends to saturate at low temperatures. Low-temperature …


[Phys. Rev. B 108, 245145] Published Tue Dec 19, 2023

Transport properties of hybrid single-bilayer graphene interfaces in a magnetic field
Nadia Benlakhouy, Ahmed Jellal, and Michael Schreiber
Author(s): Nadia Benlakhouy, Ahmed Jellal, and Michael Schreiber

We investigate the electronic properties of a hybrid system that comprises single-bilayer graphene structures subjected to a perpendicular magnetic field. Specifically, our focus is on the behavior exhibited by the zigzag boundaries of the junction, namely, zigzag-1 (ZZ1) and zigzag-2 (ZZ2), using t…


[Phys. Rev. B 108, 245419] Published Tue Dec 19, 2023

Valley coupling constructed topological two-parameter charge pump
Zixuan Ding, Donghao Wang, Yongchun Tao, and Mengyao Li
Author(s): Zixuan Ding, Donghao Wang, Yongchun Tao, and Mengyao Li

Valley coupling is proposed to construct a spatially separated two-parameter pump based on the O- or Y-shaped Kekulé (Kek) graphene superlattices (GSs) with a sandwiched graphene layer. It is shown that for the O-shaped Kek GS pumping structure, pumped charges with an integer number can be obtained …


[Phys. Rev. B 108, 245420] Published Tue Dec 19, 2023

Far-from-equilibrium criticality in the random-field Ising model with Eshelby interactions
Saverio Rossi, Giulio Biroli, Misaki Ozawa, and Gilles Tarjus
Author(s): Saverio Rossi, Giulio Biroli, Misaki Ozawa, and Gilles Tarjus

We study a quasistatically driven random-field Ising model (RFIM) at zero temperature with interactions mediated by the long-range anisotropic Eshelby kernel. Analogously to amorphous solids at their yielding transition, and differently from ferromagnetic and dipolar RFIMs, the model shows a discont…


[Phys. Rev. B 108, L220202] Published Tue Dec 19, 2023

Spin splitting and disorder of Landau levels in HgTe-based Dirac fermions
D. A. Kozlov, J. Ziegler, N. N. Mikhailov, Z. D. Kvon, and D. Weiss
Author(s): D. A. Kozlov, J. Ziegler, N. N. Mikhailov, Z. D. Kvon, and D. Weiss

This study conducts experimental exploration into a system of two-dimensional Dirac fermions utilizing a critical-thickness HgTe quantum well in weak magnetic fields. The formation and evolution of Shubnikov–de Haas oscillations in the magnetotransport and the capacitive response are studied, comple…


[Phys. Rev. B 108, L241301] Published Tue Dec 19, 2023

Found 1 papers in pr_res
Date of feed: Wed, 20 Dec 2023 04:16:53 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)

Photoinduced phases in jacutingaite monolayer
Mohammad Alipourzadeh, Yaser Hajati, and Jamal Berakdar
Author(s): Mohammad Alipourzadeh, Yaser Hajati, and Jamal Berakdar

The topological phases of monolayer jacutingaite (${\mathrm{Pt}}_{2}{\mathrm{HgSe}}_{3}$) under off-resonance high-frequency and high-intensity laser irradiation and staggered sublattice potential $V$ are investigated. The various steady-state phases are realized by an appropriate choice of the off-…


[Phys. Rev. Research 5, 043263] Published Tue Dec 19, 2023

Found 1 papers in nano-lett
Date of feed: Tue, 19 Dec 2023 14:16:00 GMT

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

[ASAP] Electroluminescence as a Probe of Strong Exciton–Plasmon Coupling in Few-Layer WSe2
Yunxuan Zhu, Jiawei Yang, Jaime Abad-Arredondo, Antonio I. Fernández-Domínguez, Francisco J. Garcia-Vidal, and Douglas Natelson

TOC Graphic

Nano Letters
DOI: 10.1021/acs.nanolett.3c04684

Found 1 papers in comm-phys


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

Resurgence of superconductivity and the role of dxy hole band in FeSe1−xTex
Amalia I. Coldea

Communications Physics, Published online: 19 December 2023; doi:10.1038/s42005-023-01481-w

The iron chalcogenide material FeSe1-xTex constitutes an important family of unconventional superconductors but its nematic phase was less explored due to a lack of single crystals. In this study, the authors provide a systematic study of the electronic structure for nematic FeSe1-xTex and observe that as the Te content increases a gradual shift and renormalization of the dxy orbital occurs, concomitant with the enhancement of superconductivity.