Found 57 papers in cond-mat
Date of feed: Fri, 29 Dec 2023 01:30:00 GMT

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Exploration of field-like torque and field-angle tunability in coupled spin-torque nano oscillators for synchronization. (arXiv:2312.16175v1 [cond-mat.mes-hall])
R. Arun, R. Gopal, V. K. Chandrasekar, M. Lakshmanan

We investigate the influence of field-like torque and the direction of the external magnetic field on a one-dimensional array of serially connected spin-torque nano oscillators, having free layers with perpendicular anisotropy, to achieve complete synchronization between them by analyzing the associated Landau-Lifshitz-Gilbert-Slonczewski equation. The obtained results for synchronization are discussed for the cases of 2, 10 and 100 oscillators separately. The roles of the field-like torque and the direction of the external field on the synchronization of the STNOs are explored through the Kuramoto order parameter. While the field-like torque alone is sufficient to bring out global synchronization in the system made up of a small number of STNOs, the direction of the external field is also needed to be slightly tuned to synchronize the one-dimensional array of a large number of STNOs. The formation of complete synchronization through the construction of clusters within the system is identified for the 100 oscillators. The large amplitude synchronized oscillations are obtained for small to large numbers of oscillators. Moreover, the tunability in frequency for a wide range of currents is shown for the synchronized oscillations up to 100 spin-torque oscillators. In addition to achieving synchronization, the field-like torque increases the frequency of the synchronized oscillations. The transverse Lyapunov exponents are deduced to confirm the stable synchronization in coupled STNOs due to the field-like torque and to validate the results obtained in the numerical simulations. The output power of the array is estimated to be enhanced substantially due to complete synchronization by the combined effect of field-like torque and tunability of the field angle.

Purity-dependent Lorenz number, electron hydrodynamics and electron-phonon coupling in WTe$_2$. (arXiv:2312.16178v1 [cond-mat.mes-hall])
Wei Xie, Feng Yang, Liangcai Xu, Xiaokang Li, Zengwei Zhu, Kamran Behnia

We present a study of electrical and thermal transport in Weyl semimetal WTe$_2$ down to 0.3 K. The Wiedemann-Franz law holds below 2 K and a downward deviation starts above. The deviation is more pronounced in cleaner samples, as expected in the hydrodynamic picture of electronic transport, where a fraction of electron-electron collisions conserve momentum. Phonons are the dominant heat carriers and their mean-free-path do not display a Knudsen minimum. This is presumably a consequence of weak anharmonicity, as indicated by the temperature dependence of the specific heat. Frequent momentum exchange between phonons and electrons leads to quantum oscillations of the phononic thermal conductivity. Bloch-Gr\"uneisen picture of electron-phonon scattering breaks down at low temperature when Umklapp ph-ph collisions cease to be a sink for electronic flow of momentum. Comparison with semi-metallic Sb shows that normal ph-ph collisions are amplified by anharmonicity. In both semimetals, at cryogenic temperature, e-ph collisions degrade the phononic flow of energy but not the electronic flow of momentum.

Nonequilibrium formulation of varying-temperature bit erasure. (arXiv:2312.16195v1 [cond-mat.stat-mech])
Stephen Whitelam

Landauer's principle states that erasing a bit of information at fixed temperature T costs at least kT ln 2 units of work. Here we investigate erasure at varying temperature, to which Landauer's result does not apply. We formulate bit erasure as a stochastic nonequilibrium process involving a compression of configuration space, with physical and logical states associated in a symmetric way. Erasure starts and ends at temperature T, but temperature can otherwise vary with time in an arbitrary way. Defined in this way, erasure is governed by a set of nonequilibrium fluctuation relations that show that varying-temperature erasure can done with less work than k T ln 2. As a result, erasure and the complementary process of bit randomization can be combined to form a work-producing engine cycle.

Massive Klein Tunneling in Topological Photonic Crystals. (arXiv:2312.16207v1 [cond-mat.mes-hall])
Keiji Nakatsugawa, Xiao Hu

Klein's paradox refers to the transmission of a relativistic particle through a high potential barrier. Although it has a simple resolution in terms of particle-to-antiparticle tunneling (Klein tunneling), debates on its physical meaning seem lasting partially due to the lack of direct experimental verification. In this article, we point out that honeycomb-type photonic crystals (PhCs) provide an ideal platform to investigate the nature of Klein tunneling, where the effective Dirac mass can be tuned in a relatively easy way from a positive value (trivial PhC) to a negative value (topological PhC) via a zero-mass case (PhC graphene). Especially, we show that analysis of the transmission between domains with opposite Dirac masses -- a case hardly be treated within the scheme available so far -- sheds new light on the understanding of the Klein tunneling.

Non-Invertible Anyon Condensation and Level-Rank Dualities. (arXiv:2312.16317v1 [hep-th])
Clay Cordova, Diego García-Sepúlveda

We derive new dualities of topological quantum field theories in three spacetime dimensions that generalize the familiar level-rank dualities of Chern-Simons gauge theories. The key ingredient in these dualities is non-abelian anyon condensation, which is a gauging operation for topological lines with non-group-like i.e. non-invertible fusion rules. We find that, generically, dualities involve such non-invertible anyon condensation and that this unifies a variety of exceptional phenomena in topological field theories and their associated boundary rational conformal field theories, including conformal embeddings, and Maverick cosets (those where standard algorithms for constructing a coset model fail.) We illustrate our discussion in a variety of isolated examples as well as new infinite series of dualities involving non-abelian anyon condensation including: i) a new description of the parafermion theory as $(SU(N)_{2} \times Spin(N)_{-4})/\mathcal{A}_{N},$ ii) a new presentation of a series of points on the orbifold branch of $c=1$ conformal field theories as $(Spin(2N)_{2} \times Spin(N)_{-2} \times Spin(N)_{-2})/\mathcal{B}_{N}$, and iii) a new dual form of $SU(2)_{N}$ as $(USp(2N)_{1} \times SO(N)_{-4})/\mathcal{C}_{N}$ arising from conformal embeddings, where $\mathcal{A}_{N}, \mathcal{B}_{N},$ and $\mathcal{C}_{N}$ are appropriate collections of gauged non-invertible bosons.

Achieving 100% amplitude modulation depth in a graphene-based tuneable capacitance metamaterial. (arXiv:2312.16330v1 [physics.optics])
Ruqiao Xia, Nikita W. Almond, Stephen J. Kindness, Sergey A. Mikhailov, Wadood Tadbier, Riccardo Degl'Innocenti, Yuezhen Lu, Abbie Lowe, Ben Ramsay, Lukas A. Jakob, James Dann, Stephan Hofmann, Harvey E. Beere, David A. Ritchie, Wladislaw Michailow

Effective control of terahertz radiation requires the development of efficient and fast modulators with a large modulation depth. This challenge is often tackled by using metamaterials, artificial sub-wavelength optical structures engineered to resonate at the desired terahertz frequency. Metamaterial-based devices exploiting graphene as the active tuneable element have been proven to be a highly effective solution for THz modulation. However, whilst the graphene conductivity can be tuned over a wide range, it cannot be reduced to zero due to the gapless nature of graphene, which directly limits the maximum achievable modulation depth for single-layer metamaterial modulators. Here, we demonstrate two novel solutions to circumvent this restriction: Firstly, we excite the modulator from the back of the substrate, and secondly, we incorporate air gaps into the graphene patches. This results in a ground-breaking graphene-metal metamaterial terahertz modulator, operating at 2.0-2.5 THz, which demonstrates a 99.01 % amplitude and a 99.99 % intensity modulation depth at 2.15 THz, with a reconfiguration speed in excess of 3 MHz. Our results open up new frontiers in the area of terahertz technology.

Convergence of Ginzburg-Landau expansions: superconductivity in the BCS theory and chiral symmetry breaking in the NJL model. (arXiv:2312.16372v1 [hep-th])
William Gyory, Naoki Yamamoto

We study the convergence of the Ginzburg-Landau (GL) expansion in the context of the Bardeen-Cooper-Schrieffer (BCS) theory for superconductivity and the Nambu-Jona-Lasinio (NJL) model for chiral symmetry breaking at finite temperature $T$ and chemical potential $\mu$. We present derivations of the all-order formulas for the coefficients of the GL expansions in both systems under the mean-field approximation. We show that the convergence radii for the BCS gap $\Delta$ and dynamical quark mass $M$ are given by $\Delta_\text{conv} = \pi T$ and $M_\text{conv} = \sqrt{\mu^2 + (\pi T)^2}$, respectively. We also discuss the implications of these results and the quantitative reliability of the GL expansion near the first-order chiral phase transition.

Structural stability, electronic band structure, and optoelectronic properties of quaternary chalcogenide CuZn2MS4 (M =In and Ga) compounds via first principles. (arXiv:2312.16390v1 [cond-mat.mtrl-sci])
Anima Ghosh, R.Thangavel

Quaternary chalcogenide compositions have been broadly explored due to their promising potential for various optoelectronic applications. The band structure, density of states and optical properties of CuZn2InS4 and CuZn2GaS4 for kesterite and stannite structures were studied with full potential augmented plane wave method (FP-LAPW) via Wien2k code. The total energy in equilibrium was calculated for different possible crystal structures and their phase stability, and transitions with p-d orbitals were analyzed. The absorption coefficient, dielectric function, and refractive index of these materials were also explored within a broad range of energy. We compared the calculated band gap values with available experimental results.

Optical probe on doping modulation of magnetic Weyl semimetal Co3Sn2S2. (arXiv:2312.16437v1 [cond-mat.mes-hall])
L. Wang (1), S. Zhang (2), B. B. Wang (2), B. X. Gao (1), L. Y. Cao (1), X. T. Zhang (1), X. Y. Zhang (1), E. K. Liu (2), R. Y. Chen (1) ((1) Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing China (2) State Key Laboratory for Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing China)

The magnetic Weyl semimetal Co3Sn2S2 is extensively investigated due to its giant anomalous Hall effect (AHE).Recent studies demonstrate that the AHE can be effectively tuned by multi-electron Ni doping.To reveal the underlying mechanism of this significant manipulation,it is crucial to explore the band structure modification caused by Ni doping.Here,we study the electrodynamics of both pristine and Ni-doped Co3-xNixSn2S2 with x=0, 0.11 and 0.17 by infrared spectroscopy. We find that the inverted energy gap around the Fermi level(EF) gets smaller at x=0.11,which is supposed to enhance the Berry curvature and therefore increase the AHE.Then EF moves out of this gap at x=0.17.Additionally,the low temperature carrier density is demonstrated to increase monotonically upon doping,which is different from previous Hall measurement results. We also observe the evidences of band broadening and exotic changes of high-energy interband transitions caused by doping.Our results provide detailed information about the band structure of Co3-xNixSn2S2 at different doping levels,which will help to guide further studies on the chemical tuning of AHE.

Dynamics of a Nonequilibrium Discontinuous Quantum Phase Transition in a Spinor Bose-Einstein Condensate. (arXiv:2312.16555v1 [cond-mat.quant-gas])
Matthew T. Wheeler, Hayder Salman, Magnus O. Borgh

Symmetry-breaking quantum phase transitions lead to the production of topological defects or domain walls in a wide range of physical systems. In second-order transitions, these exhibit universal scaling laws described by the Kibble-Zurek mechanism, but for first-order transitions a similarly universal approach is still lacking. Here we propose a spinor Bose-Einstein condensate as a testbed system where critical scaling behavior in a first-order quantum phase transition can be understood from generic properties. We generalize the Kibble-Zurek mechanism to determine the critical exponents for: (1) the onset of the decay of the metastable state on short times scales, and (2) the number of resulting phase-separated ferromagnetic domains at longer times, as a one-dimensional spin-1 condensate is ramped across a first-order quantum phase transition. The predictions are in excellent agreement with mean-field numerical simulations and provide a paradigm for studying the decay of metastable states in experimentally accessible systems.

Fractional-statistics-induced entanglement from Andreev-like tunneling. (arXiv:2312.16556v1 [cond-mat.mes-hall])
Gu Zhang, Pierre Glidic, Frederic Pierre, Igor Gornyi, Yuval Gefen

The role of anyonic statistics stands as a cornerstone in the landscape of topological quantum techniques. While recent years have brought forth encouraging and persuasive strides in detecting anyons, a significant facet remains unexplored, especially in view of connecting anyonic physics to quantum information platforms-whether and how entanglement can be generated by anyonic braiding. Here, we demonstrate that even if the two anyonic subsystems are connected only by electron tunneling, anyonic entanglement, manifesting fractional statistics, is generated. Specifically, we address this question for fractional quantum Hall edges bridged by a quantum point contact that allows only transmission of fermions (so-called Andreev-like tunneling), invoking the physics of two-beam collisions in an anyonic Hong-Ou-Mandel collider We define an entanglement pointer-a current-noise-based function tailored to quantify entanglement and show that it reflects the role of quasiparticle statistics. A striking feature of our statistics-induced-entanglement pointer is its relative resilience to entanglement stemming from electrostatic interactions between the two anyonic subsystems.

tda-segmentor: A tool to extract and analyze local structure and porosity features in porous materials. (arXiv:2312.16558v1 [cond-mat.mtrl-sci])
Aditya Vasudevan, Jorge Zorrilla Prieto, Sergei Zorkaltsev, Maciej Haranczyk

Local geometrical features of a porous material such as the shape and size of a pore or the curvature of a solid ligament often affect the macroscopic properties of the material, and their characterization is necessary to fully understand the structure-property relationships.In this contribution, we present an approach to automatically segment large porous structures into such local features. Our work takes inspiration from techniques available in Topological Data Analysis(TDA).In particular, using Morse theory, we generate Morse-Smale Complexes(MSC) of our structures that segment the structure, and/or its porosity into individual features that can then be compared. We develop a tool that is built on the topology toolkit (TTK) library, an open source platform for the topological analysis of scalar data, with which we can perform segmentation of these structures. Our tool takes a volumetric grid representation as an input, which can be generated from atomistic or mesh structure models and any function defined on such grid, e.g. the distance to the surface or the interaction energy with a probe. We demonstrate the applicability of the tool by two examples related with analysis of porosity in zeolite materials as well as analysis of ligaments in a porous metal structure. Specifically, by segmenting the pores in the structure we demonstrate some applications to zeolites such as assessing pore-similarity between structures or evaluating the accessible volume to a target molecule such as methane that can be adsorbed to its surface. Moreover, once the MSC's are generated, we can construct graph representations of the void space, replacing the entire pore structure by a simply connected graph. Similarly, the same tool is used to segment and generate graphs representing the solid structure and we show how they can be used to correlate structure and mechanical properties of the material.

Disorder driven Thouless charge pump in a quasiperiodic chain. (arXiv:2312.16568v1 [cond-mat.quant-gas])
Ashirbad Padhan, Tapan Mishra

Thouless charge pump enables a quantized transport of charge through an adiabatic evolution of the Hamiltonian exhibiting topological phase. While this charge pumping is known to be robust against the presence of weak disorder in the system, it often breaks down with the increase in disorder strength. In this work, however, we show that in a one dimensional Su-Schrieffer-Heeger lattice, a unit cell-wise staggered quasiperiodic disorder favors a quantized charge pump. Moreover, we show that such quantized Thouless charge pump is achieved by following the standard single cycle pumping protocol which usually leads to a breakdown of charge pump in other known models. This unusual property is found to be due to an emergence of a trivial gapped phase from a topological phase as the quasiperiodic disorder is tuned. This emergent gapped to gapped transition also allows us to propose a non-standard pumping scheme where a modulated disorder favors a quantized Thouless charge pump.

Combined effect of SiC and carbon on sintering kinetics, microstructure and mechanical properties of fine-grained binderless tungsten carbide. (arXiv:2312.16579v1 [cond-mat.mtrl-sci])
E.A. Lantsev (1), P.V. Andreev (1), A.V. Nokhrin (1), Yu.V. Blagoveshchenskiy (2), N.V. Isaeva (2,3), M.S. Boldin (1), A.A. Murashov (1), G.V. Shcherbak (1), K.E. Smetanina (1), V.N. Chuvil'deev (1), N.Yu. Tabachkova (3, 4) ((1) Lobachevsky State University of Nizhny Novgorod, (2) A.A. Baykov Institute of Metallurgy and Materials Science of the Russian Academy of Sciences, (3) National University of Science and Technology "MISIS", (4) A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences)

The study investigates the density, phase composition, microstructure and mechanical properties (microhardness, fracture toughness) of binderless WC + SiC and WC + SiC + C ceramics obtained by Spark Plasma Sintering (SPS). Nanopowders of a-WC produced by DC arc plasma chemical synthesis were used as raw materials. Powder compositions for sintering contained graphite (0.3, 0.5% wt.) or b-SiC (1, 3, 5% wt.) with 0.3% wt. graphite. It was shown that WC + 1% wt. SiC + 0.3% wt.C ceramics have a homogeneous fine-grained microstructure, high relative density, increased microhardness and Palmquist fracture toughness (Indentation Fracture Resistance). The kinetics of the initial sintering stage of WC + C and WC + C + SiC powder compositions was also analyzed using high-temperature dilatometry at the conventional pressureless sintering (CPS) conditions. The CPS and SPS activation energies of WC + SiC powder at the intensive shrinkage stage were determined using the Young-Cutler model. The CPS activation energies of WC, WC + C and WC + C + SiC powder compositions are close to the activation energy of diffusion of the carbon C along the a-WC grain boundaries. The SPS activation energies of WC + C and WC+ C + SiC powder compositions turn out to be lower than the activation energy of the C of a-WC grain boundary.

Topological phase transitions induced by the variation of exchange couplings in graphene. (arXiv:2312.16625v1 [cond-mat.mes-hall])
Jihyeon Park, Gun Sang Jeon

We consider a modified graphene model under exchange couplings. Various quantum anomalous phases are known to emerge under uniform or staggered exchange couplings. We introduce the twist between the orientations of two sublattice exchange couplings, which is useful for examining how such topologically nontrivial phases under different types of exchange couplings are connected to one another. The phase diagrams constructed by the variation of exchange coupling strengths and twist angles exhibit rich structures of successive topological transitions. We analyze the emergence of peculiar phases in terms of the evolution of the energy dispersions. Perturbation schemes applied to the energy levels turn out to reproduce well phase boundary lines up to moderate values of the twist angle. We also discover two close topological transitions under uniform exchange couplings, which is attributed to the interplay of the trigonal-warping deformation due to Rashba spin-orbit coupling and the staggered sublattice potential. Finally the implications of Berry curvature structure and topological excitations in real and pseudo spin textures are discussed.

Passive defect driven morphogenesis in nematic membranes. (arXiv:2312.16654v1 [cond-mat.soft])
D. J. G. Pearce, C. Thibault, Q. Chaboche, C. Blanch-Mercader

Topological defects are ubiquitous on surfaces with orientational order fields. Here, we study equilibrium states generated by the feedback between geometry and nematic order on fluid membranes with an integer topological defect. When the Frank elastic constants associated with the orientational field dominate, the surfaces spontaneously deform toward an conical shape featuring an aster topological defect at its apex. In the case of vanishing tension this is a solution to the normal force balance. We show that the stability of the surface depends on the balance of the elastic parameters and the phase of the defect. When boundary constraints are introduced, we observe three distinct modes of deformation. These deformation modes take advantage of the way in which splay, twist and bend distortions of the director field can be exchanged on a curved surface. We discuss how these deformation modes are distinguished by their response to the cost of twist distortions and the existence of inverted solutions. Our findings show that fusion of +1/2 topological defect pairs can reduce the total energy of deformable surfaces. Finally, we argue how these results can be relevant for biological systems.

Square Moir\'e Superlattices in Twisted Two-Dimensional Halide Perovskites. (arXiv:2312.16679v1 [cond-mat.mtrl-sci])
Shuchen Zhang, Linrui Jin, Yuan Lu, Linghai Zhang, Jiaqi Yang, Qiuchen Zhao, Dewei Sun, Joshua J. P. Thompson, Biao Yuan, Ke Ma, Akriti, Jee Yung Park, Yoon Ho Lee, Zitang Wei, Blake P. Finkenauer, Daria D. Blach, Sarath Kumar, Hailin Peng, Arun Mannodi-Kanakkithodi, Yi Yu, Ermin Malic, Gang Lu, Letian Dou, Libai Huang

Moir\'e superlattices have emerged as a new platform for studying strongly correlated quantum phenomena, but these systems have been largely limited to van der Waals layer two-dimensional (2D) materials. Here we introduce moir\'e superlattices leveraging ultra-thin, ligand-free halide perovskites, facilitated by ionic interactions. Square moir\'e superlattices with varying periodic lengths are clearly visualized through high-resolution transmission electron microscopy. Twist-angle-dependent transient photoluminescence microscopy and electrical characterizations indicate the emergence of localized bright excitons and trapped charge carriers near a twist angle of ~10{\deg}. The localized excitons are accompanied by enhanced exciton emission, attributed to an increased oscillator strength by a theoretically forecasted flat band. This work illustrates the potential of extended ionic interaction in realizing moir\'e physics at room temperature, broadening the horizon for future investigations.

Topological Phase Transitions in the Disordered Haldane Model. (arXiv:2312.16689v1 [cond-mat.str-el])
J. Mildner, M. D. Caio, G. Möller, N. R. Cooper, M. J. Bhaseen

We investigate the phases and phase transitions of the disordered Haldane model in the presence of on-site disorder. We use the real-space Chern marker and transfer matrices to extract critical exponents over a broad range of parameters. The disorder-driven transitions are consistent with the plateau transitions in the Integer Quantum Hall Effect (IQHE), in conformity with recent simulations of disordered Dirac fermions. Our numerical findings are compatible with an additional line of mass-driven transitions with a continuously varying correlation length exponent. The values interpolate between free Dirac fermions and the IQHE with increasing disorder strength. We also show that the fluctuations of the Chern marker exhibit a power-law divergence in the vicinity of both sets of transitions, yielding another varying exponent. We discuss the interpretation of these results.

CdTe and HgTe doped with V, Cr, and Mn -- prospects for the quantum anomalous Hall effect. (arXiv:2312.16732v1 [cond-mat.mtrl-sci])
Giuseppe Cuono, Carmine Autieri, Tomasz Dietl

Using first principle calculations we examine properties of (Cd,V)Te, (Cd,Cr)Te, (Hg,V)Te, and (Hg,Cr)Te relevant to the quantum anomalous Hall effect (QAHE), such as the position of V- and Cr- derived energy levels and the exchange interactions between magnetic ions. We consider CdTe and HgTe, containing 12.5% of cation-substitutional V or Cr ions in comparison to the well-known case of (Cd,Mn)Te and (Hg,Mn)Te, and examine their suitability for the fabrication of ferromagnetic barriers or ferromagnetic topological quantum wells, respectively. To account for the strong correlation of transition metal d electrons we employ hybrid functionals with different mixing parameters aHSE focusing on aHSE = 0.32, which better reproduces the experimental band gaps in HgTe, CdTe, Hg0.875Mn0.125Te, and Cd0.875Mn0.125Te. We find that Cr, like Mn, acts as an isoelectronic dopant but V can be an in-gap donor in CdTe and a resonant donor in HgTe, similar to the case of Fe in HgSe. From the magnetic point of view, Cr-doping results in a ferromagnetic phase within the general gradient approximation (GGA) but interactions become antiferromagnetic within hybrid functionals. However, (Hg,V)Te is a ferromagnet within both exchange-correlation functionals in a stark contrast to (Hg,Mn)Te for which robust antiferromagnetic coupling is found theoretically and experimentally. Furthermore, we establish that the Jahn-Teller effect is relevant only in the case of Cr-doping. Considering lower defect concentrations in HgTe-based quantum wells compared to (Bi,Sb)3Te2 layers, our results imply that HgTe quantum wells or (Cd,Hg)Te barriers containing either V or Cr show advantages over (Bi,Sb,Cr,V)3Te2-based QAHE systems but whether (i) ferromagnetic coupling will dominate in the Cr case and (ii) V will not introduce too many electrons to the quantum well is to be checked experimentally

Correlated Quantum Phenomena of Spin-Orbit Coupled Perovskite Oxide Heterostructures: Cases of SrRuO3 and SrIrO3-Based Artificial Superlattices. (arXiv:2312.16748v1 [cond-mat.str-el])
Seung Gyo Jeong, Jin Young Oh, Lin Hao, Jian Liu, Woo Seok Choi

Unexpected, yet useful functionalities emerge when two or more materials merge coherently. Artificial oxide superlattices realize atomic and crystal structures that are not available in nature, thus providing controllable correlated quantum phenomena. This review focuses on 4d and 5d oxide superlattices, in which the spin-orbit coupling plays a significant role compared with conventional 3d oxide superlattices. Modulations in crystal structures with octahedral distortion, phonon engineering, electronic structures, spin orderings, and dimensionality control are discussed for 4d oxide superlattices. Atomic and magnetic structures, Jeff = 1/2 pseudospin and charge fluctuations, and the integration of topology and correlation are discussed for 5d oxide superlattices. This review provides insights into how correlated quantum phenomena arise from the deliberate design of superlattice structures that give birth to novel functionalities.

Memristive behavior of functionalized graphene quantum dot and polyaniline nanocomposites. (arXiv:2312.16759v1 [cond-mat.mes-hall])
Debi Prasad Pattnaik, Abu Bakar Siddique, Alex T. Bregazzi, Pavel Borisov, Mallar Ray, Sergey Savel'ev, Niladri Banerjee

Zero-dimensional graphene quantum dots (GQD) dispersed in conducting polymer matrix display a striking range of optical, mechanical, and thermoelectric properties which can be utilized to design next-generation sensors and low-cost thermoelectric. This exotic electrical property in GQDs is achieved by exploiting the concentration of the GQDs and by tailoring the functionalization of the GQDs. However, despite extensive investigation, the nonlinear resistivity behavior leading to memristive like characteristic has not been explored much. Here, we report electrical characterisation of nitrogen functionalized GQD (NGQD) embedded in a polyaniline (PANI) matrix. We observe a strong dependence of the resistance on current and voltage history, the magnitude of which depends on the NGQD concentration and temperature. We explain this memristive property using a phenomenological model of the alignment of PANI rods with a corresponding charge accumulation arising from the NGQD on its surface. The NGQD-PANI system is unique in its ability to matrix offers a unique pathway to design neuromorphic logic and synaptic architectures with crucial advantages over existing systems.

Collective spin oscillations in a magnetized graphene sheet. (arXiv:2312.16782v1 [cond-mat.mes-hall])
M. Agarwal, O. A. Starykh, D. A. Pesin, E. G. Mishchenko

We investigate collective spin excitations of graphene electrons with short-ranged interactions and subject to the external Zeeman magnetic field. We find that in addition to the familiar Silin spin wave, a collective spin-flip excitation that reduces to the uniform precession when the wave's momentum approaches zero, the magnetized graphene supports another collective mode visible in the transverse spin susceptibility: a collective spin-current mode. Unlike the Silin wave, this mode is not dictated by the spin-rotational symmetry but rather owns its existence to the pseudo-spin structure of the graphene lattice. We find the new collective excitation to become sharply defined in a finite interval of wave's momenta, the range of which is determined by the interaction and the magnetization.

Influence of Dynamical Floquet Spectrum on the Plasmon Excitations and Exchange Energy of tilted monolayer 1T$^\prime$MoS$_2$. (arXiv:2312.16825v1 [cond-mat.mes-hall])
Sita Kandel, Godfrey Gumbs, Antonios Balassis, Andrii Iurov, Oleksiy Roslyak

It is now well established that a high-frequency electromagnetic dressing field within the off-resonance regime significantly modifies the electronic transport and optical properties on Dirac materials. Here, using light with circular polarization, we investigate its effect on the energy spectrum of tilted monolayer 1T$^\prime$MoS$_2$ which acquires two energy gaps associated with up- and down- pseudospin. We can adjust its electronic properties over a wider range by varying these two band gaps in contrast with graphene. With the use of the Lindhard approach for the frequency-dependent polarizability propagator, we have developed a rigorous theoretical formalism for employing the Floquet energy spectrum for investigating the many-body effects on the plasmon excitations, their lifetimes due to Landau damping and the exchange energy of tilted monolayer 1T$^\prime$MoS$_2$ under normal incidence of electromagnetic radiation at arbitrary temperature. The dressed states at very low temperature corresponding to circular polarization suppress the response of the system to the external probe. This gives rise to the weak but long lived plasmon excitations at small wavenumber $q$ when compared to the plasmon spectrum in this regime in the absence of irradiation. However, $\sqrt{qT}$-dependent plasmons are restored at high temperatures. Our calculations have shown that the tilting, anisotropy, direct and indirect band gaps lead to a reduced exchange energy, which has some potential applications such as, tunability of exciton polariton and plasmon excitations.

Defect bound states in the continuum without symmetry protection: bilayer graphene and beyond. (arXiv:2312.16844v1 [cond-mat.mes-hall])
Daniel Massatt, Stephen P. Shipman, Ilya Vekhter, Justin H. Wilson

We uncover a new class of bound states in the continuum in bilayer graphene, which emerges independent of symmetry protection or additional degrees of freedom. Through a comparative analysis of AA- and AB-stacked bilayer graphene, we demonstrate that these states originate from the intrinsic algebraic structure of the Hamiltonian rather than any specific underlying symmetry. This discovery paves the way for innovative approaches in defect and band-structure engineering. We conclude with a proposed protocol for observing these states in scanning tunneling microscopy experiments.

A novel two-dimensional all-carbon Dirac node-line semimetal. (arXiv:2312.16853v1 [cond-mat.mtrl-sci])
Youjie Wang, Qian Gao, Zhenpeng Hu

Carbon allotropes have vast potential in various applications, including superconductivity, energy storage, catalysis, and photoelectric semiconductor devices. Recently, there has been significant research interest in exploring new carbon materials that exhibit unique electronic structures. Here, we propose a novel two-dimensional (2D) carbon allotrope called TCH-SSH-2D, which possesses a Dirac node-line (DNL) semimetallic state. The structure of TCH-SSH-2D is derived from the TCH-type Archimedean polyhedral carbon cluster units, combined with the SSH lattice model, possessing a space group of tetragonal P4/mmm. Using first-principles calculations, we demonstrate that the system is dynamically, thermodynamically, and mechanically stable. It exhibits an energetically favorable structure with no imaginary frequency in the phonon dispersion curves and elastic constants satisfying the Born-Huang stability criterion. Our findings not only contribute to a deeper understanding of the carbon allotrope family but also provide an opportunity to explore unique Dirac states in two-dimensional pure carbon systems.

Orientational order and topological defects in a dilute solutions of rodlike polymers at low Reynolds number. (arXiv:2312.16873v1 [physics.flu-dyn])
Leonardo Puggioni, Stefano Musacchio

The relationship between the polymer orientation and the chaotic flow, in a dilute solution of rigid rodlike polymers at low Reynolds number, is investigated by means of direct numerical simulations. It is found that the rods tend to align with the velocity field in order to minimize the friction with the solvent fluid, while regions of rotational disorder are related to strong vorticity gradients, and therefore to the chaotic flow. The "turbulent-like" behavior of the system is therefore associated with the emergence and interaction of topological defects of the mean director field, similarly to active nematic turbulence. The analysis has been carried out in both two and three spatial dimensions.

Higgs-Confinement Transitions in QCD from Symmetry Protected Topological Phases. (arXiv:2312.16898v1 [hep-th])
Thomas T. Dumitrescu, Po-Shen Hsin

In gauge theories with fundamental matter there is typically no sharp way to distinguish confining and Higgs regimes, e.g. using generalized global symmetries acting on loop order parameters. It is standard lore that these two regimes are continuously connected, as has been explicitly demonstrated in certain lattice and continuum models. We point out that Higgsing and confinement sometimes lead to distinct symmetry protected topological (SPT) phases -- necessarily separated by a phase transition -- for ordinary global symmetries. We present explicit examples in 3+1 dimensions, obtained by adding elementary Higgs fields and Yukawa couplings to QCD while preserving parity P and time reversal T. In a suitable scheme, the confining phases of these theories are trivial SPTs, while their Higgs phases are characterized by non-trivial P- and T-invariant theta-angles $\theta_f, \theta_g = \pi$ for flavor or gravity background gauge fields, i.e. they are topological insulators or superconductors. Finally, we consider conventional three-flavor QCD (without elementary Higgs fields) at finite $U(1)_B$ baryon-number chemical potential $\mu_B$, which preserves P and T. At very large $\mu_B$, three-flavor QCD is known to be a completely Higgsed color superconductor that also spontaneously breaks $U(1)_B$. We argue that this high-density phase is in fact a gapless SPT, with a gravitational theta-angle $\theta_g = \pi$ that safely co-exists with the $U(1)_B$ Nambu-Goldstone boson. We explain why this SPT motivates unexpected transitions in the QCD phase diagram, as well as anomalous surface modes at the boundary of quark-matter cores inside neutron stars.

Detecting bulk carbon ferromagnetism in graphene multi-edge structure. (arXiv:2312.16925v1 [cond-mat.mtrl-sci])
Chao Wang, Nan Jian, Meijie Yin, Xi Zhang, Zhi Yang, Xiuhao Mo, Takashi Kikkawa, Shunsuke Daimon, Eiji Saitoh, Qian Li, Wensheng Yan, Dazhi Hou, Lei Yang, Dongfeng Diao

The emergence of bulk carbon ferromagnetism is long-expected over years. At nanoscale, carbon ferromagnetism was detected by analyzing the magnetic edge states via scanning tunneling microscopy(STM), and its origin can be explained by local redistribution of electron wave function. In larger scale, carbon ferromagnetism can be created by deliberately producing defects in graphite, and detected by macroscopic technical magnetization. Meanwhile, it becomes crucial to determine that the detected magnetization is originated from carbon rather than from magnetic impurities. One solution is X-ray magnetic circular dichroism (XMCD). Nonetheless, a reproducible, full section of XMCD spectrum across C-1s absorption energy has not appeared yet, which should be decisive for assuring the indisputable existence of bulk carbon ferromagnetism. Besides, the lack of direct observation on the atomic structure of the ferromagnetic carbon leaves the structural origin of its ferromagnetism still in mist. In this work, for detecting bulk carbon ferromagnetism, we managed to grow all-carbon film consisting of vertically aligned graphene multi-edge (VGME), which wove into a three-dimensional hyperfine-porous network. Magnetization (M-H) curves and XMCD spectra co-confirmed bulk carbon ferromagnetism of VGME at room temperature, with the average unit magnetic momentum of ~0.0006 miuB/atom. The influence of magnetic impurities on magnetization was excluded by both absorption spectra and inductively coupled plasma mass spectrometry measurements. The spin transfer behavior also verified the long-range and robust feature of the bulk carbon ferromagnetism. Our work provides direct evidence of elementary resolved bulk carbon ferromagnetism at room temperature and clarifies its origin from pi-electrons at graphene edges.

Solitons in binary compounds with stacked two-dimensional honeycomb lattices. (arXiv:2312.16949v1 [cond-mat.mes-hall])
James H. Muten, Louise H. Frankland, Edward McCann

We model the electronic properties of thin films of binary compounds with stacked layers where each layer is a two-dimensional honeycomb lattice with two atoms per unit cell. The two atoms per cell are assigned different onsite energies in order to consider six different stacking orders: ABC, ABA, AA, ABC$^{\prime}$, ABA$^{\prime}$, and AA$^{\prime}$. Using a minimal tight-binding model with nearest-neighbor hopping, we consider whether a fault in the texture of onsite energies in the vertical, stacking direction supports localized states, and we find localized states within the bulk band gap for ABC, ABA, and AA$^{\prime}$ stacking. Depending on the stacking type, parameter values, and whether the soliton is atomically sharp or a smooth texture, there are a range of different band structures including soliton bands that are either isolated or that hybridize with other states, such as surface states, and soliton bands that are either dispersive or flat, the latter yielding narrow features in the density of states. We discuss the relevance of our results to specific materials including graphene, hexagonal boron nitride and other binary compounds.

Topological Edge and Corner States in Biphenylene Photonic Crystal. (arXiv:2312.16952v1 [physics.optics])
Huyen Thanh Phan, Keiki Koizumi, Feng Liu, Katsunori Wakabayashi

The biphenylene network (BPN) has a unique two-dimensional atomic structure, where hexagonal unit cells are arranged on a square lattice. Inspired by such a BPN structure, we design a counterpart in the fashion of photonic crystals (PhCs), which we refer to as the BPN PhC. We study the photonic band structure using the finite element method and characterize the topological properties of the BPN PhC through the use of the Wilson loop. Our findings reveal the emergence of topological edge states in the BPN PhC, specifically in the zigzag edge and the chiral edge, as a consequence of the nontrivial Zak phase in the corresponding directions. In addition, we find the localization of electromagnetic waves at the corners formed by the chiral edges, which can be considered as second-order topological states, i.e., topological corner states.

Quantum Weyl-Heisenberg antiferromagnet. (arXiv:2312.17028v1 [cond-mat.str-el])
Peter Rosenberg, Efstratios Manousakis

Beginning from the conventional square-lattice nearest-neighbor antiferromagnetic Heisenberg model, we allow the $J_x$ and $J_y$ couplings to be anisotropic, with their values depending on the bond orientation. The emergence of anisotropic, bond-dependent, couplings should be expected to occur naturally in most antiferromagnetic compounds which undergo structural transitions that reduce the point-group symmetry at lower temperature. Using the spin-wave approximation, we study the model in several parameter regimes by diagonalizing the reduced Hamiltonian exactly, and computing the edge spectrum and Berry connection vector, which show clear evidence of localized topological charges. We discover phases that exhibit Weyl-type spin-wave dispersion, characterized by pairs of degenerate points and edge states, as well as phases supporting lines of degeneracy. We also identify a parameter regime in which there is an exotic state hosting gapless linear spin-wave dispersions with different longitudinal and transverse spin-wave velocities.

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Superconductivity in nickelate and cuprate superconductors with strong bilayer coupling. (arXiv:2312.17064v1 [cond-mat.supr-con])
Zhen Fan, Jian-Feng Zhang, Bo Zhan, Dingshun Lv, Xing-Yu Jiang, Bruce Normand, Tao Xiang

The discovery of superconductivity at 80 K under high pressure in La$_3$Ni$_2$O$_7$ presents the groundbreaking confirmation that high-$T_c$ superconductivity is a property of strongly correlated materials beyond cuprates. We use density functional theory (DFT) calculations of the band structure of La$_3$Ni$_2$O$_7$ under pressure to verify that the low-energy bands are composed almost exclusively of Ni 3$d_{x^2-y^2}$ and O 2$p$ orbitals. We deduce that the Ni 3$d_{z^2}$ orbitals are essentially decoupled by the geometry of the high-pressure structure and by the effect of the Ni Hund coupling being strongly suppressed, which results from the enhanced interlayer antiferromagnetic interaction between $d_{z^2}$ orbitals and the strong intralayer hybridization of the $d_{x^2-y^2}$ orbitals with O 2$p$. By introducing a tight-binding model for the Fermi surfaces and low-energy dispersions, we arrive at a bilayer $t$-$t_\perp$-$J$ model with strong interlayer hopping, which we show is a framework unifying La$_3$Ni$_2$O$_7$ with cuprate materials possessing similar band structures, particularly the compounds La$_2$CaCu$_2$O$_6$, Pb$_2$Sr$_2$YCu$_3$O$_8$, and EuSr$_2$Cu$_2$NbO$_8$. We use a renormalized mean-field theory to show that these systems should have ($d$+$is$)-wave superconductivity, with a dominant $d$-wave component and the high $T_c$ driven by the near-optimally doped $\beta$ band, while the $\alpha$ band adds an $s$-wave component that should lead to clear experimental signatures.

A new double-layered kagome antiferromagnet ScFe$_6$Ge$_4$. (arXiv:2312.17069v1 [cond-mat.str-el])
M. A. Kassem, T. Shiotani, H. Ohta, Y. Tabata, T. Waki, H. Nakamura

ScFe$_6$Ge$_4$ with the LiFe$_6$Ge$_4$-type structure (space group $R{\bar{3}}m$), which has a double-layered kagome lattice (18$h$ site) of Fe crystallographically equivalent to that of a well-known topological ferromagnet Fe$_3$Sn$_2$, is newly found to be antiferromagnetic (AFM) with a high N\'eel temperature of $T_{\rm{N}} \approx 650$ K, in contrast to the ferromagnetic (FM) ground state previously proposed in a literature. $^{45}$Sc nuclear magnetic resonance experiment revealed the absence of a hyperfine field at the Sc site, providing microscopic evidence for the AFM state and indicating AFM coupling between the bilayer kagome blocks. The stability of the AFM structure under the assumption of FM intra-bilayer coupling is verified by DFT calculations.

Magneto-Crystalline Composite Topological Defects and Half-Hopfions. (arXiv:2312.17083v1 [cond-mat.mes-hall])
Sahal Kaushik, Filipp N. Rybakov, Egor Babaev

We consider a new class of topological defects in chiral magnetic crystals such as FeGe and MnSi. These are composite topological defects that arise when skyrmions in the magnetic order intersect with twin boundaries in the underlying crystalline lattice. We show that the resulting stable configurations are a new type of defect that can be viewed as half-hopfions.

Multidimensional Soliton Systems. (arXiv:2312.17096v1 [nlin.PS])
Boris A. Malomed

This concise review aims to provide a summary of the most relevant recent experimental and theoretical results for solitons, i.e., self-trapped bound states of nonlinear waves, in two- and three-dimensional (2D and 3D) media. In comparison with commonly known one-dimensional solitons, which are, normally, stable modes, a challenging problem is the propensity of 2D and 3D solitons to instability, caused by the occurrence of the critical or supercritical wave collapse (catastrophic self-compression) in the same spatial dimension. A remarkable feature of multidimensional solitons is their ability to carry vorticity; however, 2D vortex rings and 3D vortex tori are subject to strong splitting instability. Therefore, it is natural to categorize the basic results according to physically relevant settings which make it possible to maintain stability of fundamental (non-topological) and vortex solitons against the collapse and splitting, respectively. The present review is focused on schemes that were recently elaborated in terms of Bose-Einstein condensates and similar photonic setups. These are two-component systems with spin-orbit coupling, and ones stabilized by the beyond-mean-field Lee-Huang-Yang effect. The latter setting has been implemented experimentally, giving rise to stable self-trapped quasi-2D and 3D "quantum droplets".

Coexistence of Dirac fermion and charge density wave in square-net-based semimetal LaAuSb2. (arXiv:2312.17143v1 [cond-mat.mtrl-sci])
Xueliang Wu, Zhixiang Hu, David Graf, Yu Liu, Chaoyue Deng, Huixia Fu, Asish K. Kundu, Tonica Valla, Cedomir Petrovic, Aifeng Wang

We report a comprehensive study of magnetotransport properties, angle-resolved photoemission spectroscopy (ARPES), and density functional theory (DFT) calculations on self-flux grown LaAuSb$_2$ single crystals. Resistivity and Hall measurements reveal a charge density wave (CDW) transition at 77 K. MR and de Haas-Van Alphen (dHvA) measurements indicate that the transport properties of LaAuSb$_2$ are dominated by Dirac fermions that arise from Sb square nets. ARPES measurements and DFT calculations reveal an electronic structure with a common feature of the square-net-based topological semimetals, which is in good agreement with the magnetotransport properties. Our results indicate the coexistence of CDW and Dirac fermion in LaAuSb$_2$, both of which are linked to the bands arising from the Sb-square net, suggesting that the square net could serve as a structural motif to explore various electronic orders.

SymTFT out of equilibrium: from time crystals to braided drives and Floquet codes. (arXiv:2312.17176v1 [cond-mat.str-el])
Vedant Motamarri, Campbell McLauchlan, Benjamin Béri

Symmetry Topological Field Theory (SymTFT) is a framework to capture universal features of quantum many-body systems by viewing them as a boundary of topological order in one higher dimension. This yielded numerous insights in static low-energy settings. Here we study what SymTFT can tell about nonequilibrium, focusing on one-dimensional (1D) driven systems and their 2D SymTFT. In driven settings, boundary conditions (BCs) can be dynamical and can apply both spatially and temporally. We show how this enters SymTFT via topological operators, which we then use to uncover several new results for 1D dynamics. These include revealing time crystals (TCs) as systems with symmetry-twisted temporal BCs, finding robust bulk TC features in phases thought to be only boundary TCs, Floquet dualities, or identifying Floquet codes as space-time duals to systems with duality-twisted spatial BCs. We also show how, by making duality-twisted BCs dynamical, non-Abelian braiding of duality defects can enter SymTFT, leading to effects such as the exact pumping of symmetry charges between a system and its BCs. We illustrate our ideas for $\mathbb{Z}_2$-symmetric 1D systems, but our construction applies for any finite Abelian symmetry.

Tunable even- and odd-denominator fractional quantum Hall states in trilayer graphene. (arXiv:2312.17204v1 [cond-mat.mes-hall])
Yiwei Chen, Yan Huang, Qingxin Li, Bingbing Tong, Guangli Kuang, Chuanying Xi, Kenji Watanabe, Takashi Taniguchi, Guangtong Liu, Zheng Zhu, Li Lu, Fu-Chun Zhang, Ying-Hai Wu, Lei Wang

The fractional quantum Hall (FQH) states are exotic quantum many-body phases whose elementary charged excitations are neither bosons nor fermions but anyons, obeying fractional braiding statistics. While most FQH states are believed to have Abelian anyons, the Moore-Read type states with even denominators, appearing at half filling of a Landau level (LL), are predicted to possess non-Abelian excitations with appealing potentials in topological quantum computation. These states, however, depend sensitively on the orbital contents of the single-particle LL wavefunction and the mixing between different LLs. Although they have been observed in a few materials, their non-Abelian statistics still awaits experimental confirmation. Here we show magnetotransport measurements on Bernal-stacked trilayer graphene (TLG), whose unique multiband structure facilitates the interlaced LL mixing, which can be controlled by external magnetic and displacement fields. We observe a series of robust FQH states including even-denominator ones at filling factors $\nu=-9/2$, $-3/2$, $3/2$ and $9/2$. In addition, we are able to finetune the LL mixing and crossings to drive quantum phase transitions of these half-filling states and their neighboring odd-denominator ones, exhibiting a related emerging and waning behavior. Our results establish TLG as a controllable system for tuning the weights of LL orbitals and mixing strength, and a fresh platform to seek for non-Abelian quasi-particles.

Possible Unconventional Surface Superconductivity in the Half-Heusler YPtBi. (arXiv:2312.17213v1 [cond-mat.supr-con])
Eylon Persky, Alan Fang, Xinyang Zhang, Carolina Adamo, Eli Levenson-Falk, Chandra Shekhar, Claudia Felser, Binghai Yan, Aharon Kapitulnik

We report an extensive extensive study of the noncentrosymmetric half-Heusler topological superconductor YPtBi, revealing unusual relation between bulk superconductivity and the appearance of surface superconductivity at temperatures up to 3 times the bulk transition temperature. Transport measurements confirmed the low carrier density of the material and its bulk superconducting transition, which was also observed in ac susceptibility through mutual inductance (MI) measurements. However, a weak signature of superconductivity in the MI measurements appeared much above the bulk transition temperature, which was further observed in scanning tunneling spectroscopy. Polar Kerr effect measurements suggest that while the bulk superconductor may exhibit an unusual nodal superconducting state, only the surface state breaks time reversal symmetry. Complementary tunneling measurements on LuPtBi are used to establish the observations on YPtBi, while density-functional theory (DFT) calculations may shed light on the origin of this unusual surface state.

Non-Abelian Three-Loop Braiding Statistics for 3D Fermionic Topological Phases. (arXiv:1912.13505v2 [cond-mat.str-el] UPDATED)
Jing-Ren Zhou, Qing-Rui Wang, Chenjie Wang, Zheng-Cheng Gu

Fractional statistics is one of the most intriguing features of topological phases in 2D. In particular, the so-called non-Abelian statistics plays a crucial role towards realizing universal topological quantum computation. Recently, the study of topological phases has been extended to 3D and it has been proposed that loop-like extensive objects can also carry fractional statistics. In this work, we systematically study the so-called three-loop braiding statistics for loop-like excitations for 3D fermionic topological phases. Most surprisingly, we discovered new types of non-Abelian three-loop braiding statistics that can only be realized in fermionic systems (or equivalently bosonic systems with fermionic particles). The simplest example of such non-Abelian braiding statistics can be realized in interacting fermionic systems with a gauge group $\mathbb{Z}_2 \times \mathbb{Z}_8$ or $\mathbb{Z}_4 \times \mathbb{Z}_4$, and the physical origin of non-Abelian statistics can be viewed as attaching an open Majorana chain onto a pair of linked loops, which will naturally reduce to the well known Ising non-Abelian statistics via the standard dimension reduction scheme. Moreover, due to the correspondence between gauge theories with fermionic particles and classifying fermionic symmetry-protected topological (FSPT) phases with unitary symmetries, our study also give rise to an alternative way to classify FSPT phases with unitary symmetries. We further compare the classification results for FSPT phases with arbitrary Abelian total symmetry $G^f$ and find systematical agreement with previous studies using other methods. We believe that the proposed framework of understanding three-loop braiding statistics (including both Abelian and non-Abelian cases) in interacting fermion systems applies for generic fermonic topological phases in 3D.

Towards a complete classification of non-chiral topological phases in 2D fermion systems. (arXiv:2112.06124v2 [cond-mat.str-el] UPDATED)
Jing-Ren Zhou, Qing-Rui Wang, Zheng-Cheng Gu

In recent years, fermionic topological phases of quantum matter has attracted a lot of attention. In a pioneer work by Gu, Wang and Wen, the concept of equivalence classes of fermionic local unitary(FLU) transformations was proposed to systematically understand non-chiral topological phases in 2D fermion systems and an incomplete classification was obtained. On the other hand, the physical picture of fermion condensation and its corresponding super pivotal categories give rise to a generic mathematical framework to describe fermionic topological phases of quantum matter. In particular, it has been pointed out that in certain fermionic topological phases, there exists the so-called q-type anyon excitations, which have no analogues in bosonic theories. In this paper, we generalize the Gu, Wang and Wen construction to include those fermionic topological phases with q-type anyon excitations. We argue that all non-chiral fermionic topological phases in 2+1D are characterized by a set of tensors $(N^{ij}_{k},F^{ij}_{k},F^{ijm,\alpha\beta}_{kln,\chi\delta},n_{i},d_{i})$, which satisfy a set of nonlinear algebraic equations parameterized by phase factors $\Xi^{ijm,\alpha\beta}_{kl}$, $\Xi^{ij}_{kln,\chi\delta}$, $\Omega^{kim,\alpha\beta}_{jl}$ and $\Omega^{ki}_{jln,\chi\delta}$. Moreover, consistency conditions among algebraic equations give rise to additional constraints on these phase factors which allow us to construct a topological invariant partition for an arbitrary triangulation of 3D spin manifold. Finally, several examples with q-type anyon excitations are discussed, including the Fermionic topological phase from Tambara-Yamagami category for $\mathbb{Z}_{2N}$, which can be regarded as the $\mathbb{Z}_{2N}$ parafermion generalization of Ising fermionic topological phase.

Indirect exciton-phonon dynamics in MoS2 revealed by ultrafast electron diffraction. (arXiv:2112.15240v2 [cond-mat.mes-hall] UPDATED)
Jianbo Hu, Yang Xiang, Beatrice Matilde Ferrari, Emilio Scalise, Giovanni Maria Vanacore

Transition metal dichalcogenides layered nano-crystals are emerging as promising candidates for next-generation optoelectronic and quantum devices. In such systems, the interaction between excitonic states and atomic vibrations is crucial for many fundamental properties, such as carrier mobilities, quantum coherence loss, and heat dissipation. In particular, to fully exploit their valley-selective excitations, one has to understand the many-body exciton physics of zone-edge states. So far, theoretical and experimental studies have mainly focused on the exciton-phonon dynamics in high-energy direct excitons involving zone-center phonons. Here, we use ultrafast electron diffraction and ab initio calculations to investigate the many-body structural dynamics following nearly-resonant excitation of low-energy indirect excitons in MoS2. By exploiting the large momentum carried by scattered electrons, we identify the excitation of in-plane K- and Q-phonon modes with E^' symmetry as key for the stabilization of indirect excitons generated via near-infrared light at 1.55 eV, and we shed light on the role of phonon anharmonicity and the ensuing structural evolution of the MoS2 crystal lattice. Our results highlight the strong selectivity of phononic excitations directly associated with the specific indirect-exciton nature of the wavelength-dependent electronic transitions triggered in the system.

Bulk-boundary correspondence in point-gap topological phases. (arXiv:2205.15635v3 [cond-mat.mes-hall] UPDATED)
Daichi Nakamura, Takumi Bessho, Masatoshi Sato

A striking feature of non-Hermitian systems is the presence of two different types of topology. One generalizes Hermitian topological phases, and the other is intrinsic to non-Hermitian systems, which are called line-gap topology and point-gap topology, respectively. Whereas the bulk-boundary correspondence is a fundamental principle in the former topology, its role in the latter has not been clear yet. This paper establishes the bulk-boundary correspondence in the point-gap topology in non-Hermitian systems. After revealing the requirement for point-gap topology in the open boundary conditions, we clarify that the bulk point-gap topology in open boundary conditions can be different from that in periodic boundary conditions. We give a complete classification of the open boundary point-gap topology with symmetry and show that the non-trivial open boundary topology results in robust and exotic surface states.

Role of Topology in Relaxation of One-Dimensional Stochastic Processes. (arXiv:2301.09832v3 [cond-mat.stat-mech] UPDATED)
Taro Sawada, Kazuki Sone, Ryusuke Hamazaki, Yuto Ashida, Takahiro Sagawa

Stochastic processes are commonly used models to describe dynamics of a wide variety of nonequilibrium phenomena ranging from electrical transport to biological motion. The transition matrix describing a stochastic process can be regarded as a non-Hermitian Hamiltonian. Unlike general non-Hermitian systems, the conservation of probability imposes additional constraints on the transition matrix, which can induce unique topological phenomena. Here, we reveal the role of topology in relaxation phenomena of classical stochastic processes. Specifically, we define a winding number that is related to topology of stochastic processes and show that it predicts the existence of a spectral gap that characterizes the relaxation time. Then, we numerically confirm that the winding number corresponds to the system-size dependence of the relaxation time and the characteristic transient behavior. One can experimentally realize such topological phenomena in magnetotactic bacteria and cell adhesions.

Searching for Unconventional Superfluid in Excitons of Monolayer Semiconductors. (arXiv:2302.05585v2 [cond-mat.quant-gas] UPDATED)
Wei Chen, Chun-Jiong Huang, Qizhong Zhu

It is well known that two-dimensional (2D) bosons in homogeneous space cannot undergo real Bose-Einstein condensation, and the superfluid to normal phase transition is Berezinskii-Kosterlitz-Thouless (BKT) type, associated with vortex-antivortex pair unbinding. Here we point out a 2D bosonic system whose low energy physics goes beyond conventional paradigm of 2D {\it homogeneous} bosons, i.e., intralayer excitons in monolayer transition metal dichalcogenides. With intrinsic valley-orbit coupling and valley Zeeman energy, exciton dispersion becomes linear at small momentum, giving rise to a series of novel features. The critical temperature of Bose-Einstein condensation of these excitons is nonzero, suggesting true long-range order in 2D homogeneous system. The dispersion of Goldstone mode at long wavelength has the form $\varepsilon(\boldsymbol{q})\sim\sqrt{q}$, in contrast to conventional linear phonon spectrum. The vortex energy deviates from the usual logarithmic form with respect to system size, but instead has an additional linear term. Superfluid to normal phase transition is no longer BKT type for system size beyond a characteristic scale, without discontinuous jump in superfluid density. With the recent experimental progress on exciton fluid at thermal equilibrium in monolayer semiconductors, our work points out an experimentally accessible system to search for unconventional 2D superfluids beyond BKT paradigm.

Chiral pair density wave as a precursor of the pseudogap in kagom\'e superconductors. (arXiv:2306.06242v2 [cond-mat.supr-con] UPDATED)
Narayan Mohanta

Motivated by scanning tunneling microscopy experiments on $A$V$_3$Sb$_5$ ($A$ = Cs, Rb, K) that revealed periodic real-space modulation of electronic states at low energies, I show using model calculations that a triple-{\bf Q} chiral pair density wave (CPDW) is generated in the superconducting state by a charge order of $2a\! \times \!2a$ superlattice periodicity, intertwined with a time-reversal symmetry breaking orbital loop current. In the presence of such a charge order and orbital loop current, the superconducting critical field is enhanced beyond the Chandrasekhar-Clogston limit. The CPDW correlation survives even when the long-range superconducting phase coherence is diminished by a magnetic field or temperature, stabilizing an exotic granular superconducting state above and in the vicinity of the superconducting transition. The presented results suggest that the CPDW can be regarded as the origin of the pseudogap observed near the superconducting transition.

Signature of geometry modulation on interface magnetism emerged in isomeric IrO2-CoFe2O4 heterostructures. (arXiv:2307.07169v2 [cond-mat.mtrl-sci] UPDATED)
Meng Wang, Shunsuke Mori, Xiuzhen Yu, Masahiro Sawada, Naoya Kanazawa, Pu Yu, Fumitaka Kagawa

The interface composed of magnets and strong spin-orbit coupling (SOC) materials forms an important platform for spintronic devices and intriguing magnetic phenomena, such as the chiral spin textures and magnetic proximity effect (MPE). The interface exchange interaction and Dzyaloshinskii-Moriya interaction (DMI) have been discussed in a wide range of heterostructures, while the crystal stacking geometry modulation on these interface interactions has rarely been considered. Here, we show a pronounced geometry modulation on the interface magnetism through comparing a rutile and an anatase IrO2 capping on a ferrimagnetic CoFe2O4. The rutile heterostructure with a high-symmetry interface shows a conventional anomalous Hall effect (AHE) profile due to the MPE. In contrast, the anatase one with a low-symmetry interface exhibits a topological-like AHE even at zero-field, suggesting the emergence of non-coplanar magnetic order at the interface. Our results suggest that the influence of DMI at the interface can be more accentuated by forming a low-symmetry interface and raises a new means of designing interface magnetism via the geometry modulation.

Nonequilibrium phase transitions in a Brownian $p$-state clock model. (arXiv:2307.09945v2 [cond-mat.stat-mech] UPDATED)
Chul-Ung Woo, Jae Dong Noh

We introduce a Brownian $p$-state clock model in two dimensions and investigate the nature of phase transitions numerically. As a nonequilibrium extension of the equilibrium lattice model, the Brownian $p$-state clock model allows spins to diffuse randomly in the two-dimensional space of area $L^2$ under periodic boundary conditions. We find three distinct phases for $p>4$: a disordered paramagnetic phase, a quasi-long-range-ordered critical phase, and an ordered ferromagnetic phase. In the intermediate critical phase, the magnetization order parameter follows a power law scaling $m \sim L^{-\tilde{\beta}}$, where the finite-size scaling exponent $\tilde{\beta}$ varies continuously. These critical behaviors are reminiscent of the double Berezinskii-Kosterlitz-Thouless~(BKT) transition picture of the equilibrium system. At the transition to the disordered phase, the exponent takes the universal value $\tilde\beta = 1/8$ which coincides with that of the equilibrium system. This result indicates that the BKT transition driven by the unbinding of topological excitations is robust against the particle diffusion. On the contrary, the exponent at the symmetry-breaking transition to the ordered phase deviates from the universal value $\tilde{\beta} = 2/p^2$ of the equilibrium system. The deviation is attributed to a nonequilibrium effect from the particle diffusion.

Understanding the role of Hubbard corrections in the rhombohedral phase of BaTiO$_3$. (arXiv:2309.04348v2 [cond-mat.mtrl-sci] UPDATED)
G. Gebreyesus, Lorenzo Bastonero, Michele Kotiuga, Nicola Marzari, Iurii Timrov

We present a first-principles study of the low-temperature rhombohedral phase of BaTiO$_3$ using Hubbard-corrected density-functional theory. By employing density-functional perturbation theory, we compute the onsite Hubbard $U$ for Ti($3d$) states and the intersite Hubbard $V$ between Ti($3d$) and O($2p$) states. We show that applying the onsite Hubbard $U$ correction alone to Ti($3d$) states proves detrimental, as it suppresses the Ti($3d$)-O($2p$) hybridization and drives the system towards a cubic phase. Conversely, when both onsite $U$ and intersite $V$ are considered, the localized character of the Ti($3d$) states is maintained, while also preserving the Ti($3d$)-O($2p$) hybridization, restoring the rhombohedral phase of BaTiO$_3$. The generalized PBEsol+$U$+$V$ functional yields good agreement with experimental results for the band gap and dielectric constant, while the optimized geometry is slightly less accurate compared to PBEsol. Zone-center phonon frequencies and Raman spectra are found to be significantly influenced by the underlying geometry. PBEsol and PBEsol+$U$+$V$ provide satisfactory agreement with the experimental Raman spectrum when the PBEsol geometry is used, while PBEsol+$U$ Raman spectrum diverges strongly from experimental data highlighting the adverse impact of the $U$ correction alone in BaTiO$_3$. Our findings underscore the promise of the extended Hubbard PBEsol+$U$+$V$ functional with first-principles $U$ and $V$ for the investigation of other ferroelectric perovskites with mixed ionic-covalent interactions.

Electrical Control of Two-Dimensional Electron-Hole Fluids in the Quantum Hall Regime. (arXiv:2309.04600v2 [cond-mat.mes-hall] UPDATED)
Bo Zou, Yongxin Zeng, A.H. MacDonald, Artem Strashko

We study the influence of quantizing perpendicular magnetic fields on the ground state of a bilayer with electron and hole fluids separated by an opaque tunnel barrier. In the absence of a field, the ground state at low carrier densities is a condensate of s-wave excitons that has spontaneous interlayer phase coherence. We find that a series of phase transitions emerge at strong perpendicular fields between condensed states and incompressible incoherent states with full electron and hole Landau levels. When the electron and hole densities are unequal, condensation can occur in higher angular momentum electron-hole pair states and, at weak fields, break rotational symmetry. We explain how this physics is expressed in dual-gate phase diagrams, and predict transport and capacitively-probed thermodynamic signatures that distinguish different states.

Fractional Quantum Anomalous Hall Effect in a Graphene Moire Superlattice. (arXiv:2309.17436v4 [cond-mat.mes-hall] UPDATED)
Zhengguang Lu, Tonghang Han, Yuxuan Yao, Aidan P. Reddy, Jixiang Yang, Junseok Seo, Kenji Watanabe, Takashi Taniguchi, Liang Fu, Long Ju

The fractional quantum anomalous Hall effect (FQAHE), the analog of the fractional quantum Hall effect1 at zero magnetic field, is predicted to exist in topological flat bands under spontaneous time-reversal-symmetry breaking. The demonstration of FQAHE could lead to non-Abelian anyons which form the basis of topological quantum computation. So far, FQAHE has been observed only in twisted MoTe2 (t-MoTe2) at moire filling factor v > 1/2. Graphene-based moire superlattices are believed to host FQAHE with the potential advantage of superior material quality and higher electron mobility. Here we report the observation of integer and fractional QAH effects in a rhombohedral pentalayer graphene/hBN moire superlattice. At zero magnetic field, we observed plateaus of quantized Hall resistance Rxy = h/(ve^2) at filling factors v = 1, 2/3, 3/5, 4/7, 4/9, 3/7 and 2/5 of the moire superlattice respectively. These features are accompanied by clear dips in the longitudinal resistance Rxx. In addition, at zero magnetic field, Rxy equals 2h/e^2 at v = 1/2 and varies linearly with the filling factor-similar to the composite Fermi liquid (CFL) in the half-filled lowest Landau level at high magnetic fields. By tuning the gate displacement field D and v, we observed phase transitions from CFL and FQAH states to other correlated electron states. Our graphene system provides an ideal platform for exploring charge fractionalization and (non-Abelian) anyonic braiding at zero magnetic field, especially considering a lateral junction between FQAHE and superconducting regions in the same device.

Defect-influenced particle advection in highly confined liquid crystal flows. (arXiv:2310.18667v2 [cond-mat.soft] UPDATED)
Magdalena Lesniewska, Nigel Mottram, Oliver Henrich

We study the morphology of the Saturn ring defect and director structure around a colloidal particle with normal anchoring conditions and within the flow of the nematic host phase through a rectangular duct of comparable size to the particle. The changes in the defect structures and director profile influence the advection behaviour of the particle, which we compare to that in a simple Newtonian host phase. These effects lead to a non-monotonous dependence of the differential velocity of particle and fluid, also known as retardation ratio, on the Ericksen number.

Signature of Topological Semimetal in Harmonic-honeycomb ReO3. (arXiv:2310.20341v2 [cond-mat.mtrl-sci] UPDATED)
Yifeng Han, Cui-Qun Chen, Hualei Sun, Shuang Zhao, Long Jiang, Yuxuan Liu, Zhongxiong Sun, Meng Wang, Hongliang Dong, Ziyou Zhang, Zhiqiang Chen, Bin Chen, Dao-Xin Yao, Man-Rong Li

Transition-metal honeycomb compounds are capturing scientific attention due to their distinctive electronic configurations, underscored by the triangular-lattice spin-orbit coupling and competition between multiple interactions, paving the way for potential manifestations of phenomena such as Dirac semimetal, superconductivity, and quantum spin liquid states. These compounds can undergo discernible pressure-induced alterations in their crystallographic and electronic paradigms, as exemplified by our high-pressure (HP) synthesis and exploration of the honeycomb polymorph of ReO3 (P6322). This HP-P6322 polymorph bears a phase transition from P6322 to P63/mmc upon cooling around Tp = 250 K, as evidenced by the evolution of temperature-dependent magnetization (M-T curves), cell dimension, and conductivity initiated by an inherent bifurcation of the oxygen position in the ab plane. Insightful analysis of its band structure positions suggests this HP-P6322 polymorph being a plausible candidate for Dirac semimetal properties. This phase transition evokes anomalies in the temperature-dependent variation of paramagnetism (non-linearity) and a crossover from semiconductor to temperature-independent metal, showing a temperature independent conductivity behavior below ~200 K. Under increasing external pressure, both the Tp and resistance of this HP-polymorph is slightly magnetic-field dependent and undergo a "V"-style evolution (decreasing and then increasing) before becoming pressure independent up to 20.2 GPa. Theoretical calculations pinpoint this anionic disorder as a probable catalyst for the decrement in the conductive efficiency and muted temperature-dependent conductivity response.

Phase diagram near the quantum critical point in Schwinger model at $\theta = \pi$: analogy with quantum Ising chain. (arXiv:2311.04738v2 [hep-lat] UPDATED)
Hiroki Ohata

The Schwinger model, one-dimensional quantum electrodynamics, has CP symmetry at $\theta = \pi$ due to the topological nature of the $\theta$ term. At zero temperature, it is known that as increasing the fermion mass, the system undergoes a second-order phase transition to the CP broken phase, which belongs to the same universality class as the quantum Ising chain. In this paper, we obtain the phase diagram near the quantum critical point (QCP) in the temperature and fermion mass plane using first-principle Monte Carlo simulations, while avoiding the sign problem by using the lattice formulation of the bosonized Schwinger model. Specifically, we perform a detailed investigation of the correlation function of the electric field near the QCP and find that its asymptotic behavior can be described by the universal scaling function of the quantum Ising chain. This finding indicates the existence of three regions near the QCP, each characterized by a specific asymptotic form of the correlation length, and demonstrates that the CP symmetry is restored at any nonzero temperature, entirely analogous to the quantum Ising chain. The range of the scaling behavior is also examined and found to be particularly wide.

Hofstadter quasicrystals, hidden symmetries and irrational quantum oscillations. (arXiv:2311.16967v2 [cond-mat.mes-hall] UPDATED)
Kirill Kozlov, Grigor Adamyan, Mariia Kryvoruchko, Yelizaveta Kulynych, Leonid Levitov

Landau levels perturbed by a periodic potential is a prime setting to design quantum systems with exotic fractal spectra. Motivated by recent advances in twistronics, we introduce `Hofstadter quasicrystal' problem describing Landau levels perturbed by a set of incommensurate cosine waves. We illustrate the underlying physics for moir\'{e} quasicrystals with octagonal and dodecagonal symmetries, finding spectra that are vastly more complex than the Hofstadter spectrum. Surprisingly, due to the high spatial symmetry, the quasicrystal problem exhibits hidden `inner' symmetry arising at special `magic' values of the magnetic field. The $1/B$-periodic pattern of magic field values explains striking wide-range oscillations in the observed spectra that have irrational periodicity incommensurate with the Aharonov-Bohm and Brown-Zak periodicities. The prominent character of these oscillations makes them readily accessible in state-of-the-art moir\'{e} graphene systems.

Strain-driven Charge Localisation and Spin Dynamics of Paramagnetic Defects in S-deficit 2H-MoS2 Nanocrystals. (arXiv:2312.12805v2 [cond-mat.mtrl-sci] UPDATED)
Sudipta Khamrui, Kamini Bharti, Daniella Goldfarb, Tilak Das, Debamalya Banerjee

A microscopic control over the origin and dynamics of localised spin centres in lower dimensional solids turns out to be a key factor for next generation spintronics and quantum technologies. With the help of low temperature electron paramagnetic resonance (EPR) measurements, supported by the first-principles calculations within density functional theory (DFT) formulation, we found the origin of different high-spin paramagnetic intrinsic charge-centres, Mo3+(4d3) and Mo2+(4d4) present in the nano-crystalline sulfur deficit hexagonal molybdenum disulfide (2H-MoS_(2-x)), against the established notion of spin-1/2 , Mo5+ centres. A critical strain generated in the nano-structured 2H-MoS_(2-x) was found to be very crucial for spin-localization in this layered material. Indeed, computationally effective proposition of the PBE+U exchange-correlations within DFT including D3-dispersion corrections found to be more viable than expensive higher rung of exchange-correlation functionals, explored earlier. It is also found that the oxygen vacancy of the reduced oxide phase, embedded in 2H-MoS_(2-x) host lattice, has the longest relaxation times. Moreover, the temperature dependence of spin-lattice relaxation measurements reveals a direct process for interstitial spin centres and a Raman process for both sulfur and oxygen vacancy sites. We expect such observation would be a valuable pillar for better understanding of the next generation quantum technologies and device applications.

Quantum-criticality in twisted bi-layer graphene. (arXiv:2312.15410v2 [cond-mat.str-el] UPDATED)
C. M. Varma

Transport experiments in twisted bilayer graphene (TBG) show a fan-like region near integer fillings with a resistivity linear in temperature down to the lowest temperature measured. This suggests quantum-critical points at the boundaries to long-range ordered phases. The particular order proposed by Blutinck et al. for twisted bi-layer graphene (TBG) is a loop-current order at the carbon length-scale together with modulations on the moir\'e length scale. This is shown to be the ground state of a xy model with translational symmetry and time-reversal broken. Here, this is extended to derive a model for quantum-critical properties. We derive the quantum xy model coupled to fermions in this situation. The kinetic energy operator for the model and the coupling of fermions to the fluctuations of the xy model are derived. The previously derived universal properties in the quantum-critical region of such a model, leading to a marginal Fermi-liquid, irrespective of the underlying microscopics is briefly reviewed. The properties include the resistivity and various other transport properties with and without applying a magnetic field and the instability of the quantum fluctuating state to superconductivity in d-wave symmetry.

Found 3 papers in prb
Date of feed: Fri, 29 Dec 2023 04:16:57 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)

Van Hove singularity–induced negative magnetoresistance in Dirac semimetals
Kai-He Ding and Zhen-Gang Zhu
Author(s): Kai-He Ding and Zhen-Gang Zhu

Negative magnetoresistance (NMR) is a marked feature of Dirac semimetals, and may be caused by multiple mechanisms, such as the chiral anomaly, the Zeeman energy, the quantum interference effect, and the orbital moment. Recently, an experiment on Dirac semimetal ${\mathrm{Cd}}_{3}{\mathrm{As}}_{2}$ …

[Phys. Rev. B 108, 245158] Published Thu Dec 28, 2023

Toward a global phase diagram of the fractional quantum anomalous Hall effect
Aidan P. Reddy and Liang Fu
Author(s): Aidan P. Reddy and Liang Fu

Recent experiments on tMoTe2 provide the first realization of the fractional quantum anomalous Hall effect. Synthesizing insights from an extensive exact diagonalization study, the authors present here a many-body phase diagram tMoTe2, in which lowest Landau level (LLL)-like features and non-LLL-like features coexist. The study highlights several guiding principles, including interaction-enhanced particle-hole asymmetry, that is expected to play an important role in general fractional quantum anomalous Hall systems.

[Phys. Rev. B 108, 245159] Published Thu Dec 28, 2023

Metallic quantized anomalous Hall effect without chiral edge states
Kai-Zhi Bai, Bo Fu, Zhenyu Zhang, and Shun-Qing Shen
Author(s): Kai-Zhi Bai, Bo Fu, Zhenyu Zhang, and Shun-Qing Shen

The quantum anomalous Hall effect (QAHE) is a topological state of matter with a quantized Hall resistance. It has been observed in some two-dimensional insulating materials such as magnetic topological insulator films and twisted bilayer graphene. These materials are insulating in the bulk but poss…

[Phys. Rev. B 108, L241407] Published Thu Dec 28, 2023

Found 3 papers in prl
Date of feed: Fri, 29 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)

Photonic Spin Hopfions and Monopole Loops
Haiwen Wang and Shanhui Fan
Author(s): Haiwen Wang and Shanhui Fan

Spin textures with various topological orders are of great theoretical and practical interest. Hopfion, a spin texture characterized by a three-dimensional topological order was recently realized in electronic spin systems. Here, we show that monochromatic light can be structured such that its photo…

[Phys. Rev. Lett. 131, 263801] Published Thu Dec 28, 2023

Expanding the Pressure Frontier in Grüneisen Parameter Measurement: Study of Sodium Chloride
Jun Kong, Kaiyuan Shi, Xingbang Dong, Xiao Dong, Xin Zhang, Jiaqing Zhang, Lei Su, and Guoqiang Yang
Author(s): Jun Kong, Kaiyuan Shi, Xingbang Dong, Xiao Dong, Xin Zhang, Jiaqing Zhang, Lei Su, and Guoqiang Yang

The Grüneisen parameter ($γ$) is crucial for determining many thermal properties, including the anharmonic effect, thermostatistics, and equation of state of materials. However, the isentropic adiabatic compression conditions required to measure the Grüneisen parameter under high pressure are diffic…

[Phys. Rev. Lett. 131, 266101] Published Thu Dec 28, 2023

Density-Polarity Coupling in Confined Active Polar Films: Asters, Spirals, and Biphasic Orientational Phases
Mathieu Dedenon, Claire A. Dessalles, Pau Guillamat, Aurélien Roux, Karsten Kruse, and Carles Blanch-Mercader
Author(s): Mathieu Dedenon, Claire A. Dessalles, Pau Guillamat, Aurélien Roux, Karsten Kruse, and Carles Blanch-Mercader

Topological defects in active polar fluids can organize spontaneous flows and influence macroscopic density patterns. Both of them play an important role during animal development. Yet the influence of density on active flows is poorly understood. Motivated by experiments on cell monolayers confined…

[Phys. Rev. Lett. 131, 268301] Published Thu Dec 28, 2023

Found 9 papers in nano-lett
Date of feed: Thu, 28 Dec 2023 22:18:02 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] Tip Growth of Quasi-Metallic Bilayer Graphene Nanoribbons with Armchair Chirality
Shuo Lou, Bosai Lyu, Jiajun Chen, Xianliang Zhou, Wenwu Jiang, Lu Qiu, Peiyue Shen, Saiqun Ma, Zhichun Zhang, Yufeng Xie, Zhenghan Wu, Yi Chen, Kunqi Xu, Qi Liang, Kenji Watanabe, Takashi Taniguchi, Lede Xian, Guangyu Zhang, Wengen Ouyang, Feng Ding, and Zhiwen Shi

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Nano Letters
DOI: 10.1021/acs.nanolett.3c03534

[ASAP] Anomalous Hall Transport by Optically Injected Isospin Degree of Freedom in Dirac Semimetal Thin Film
Yuta Murotani, Natsuki Kanda, Tomohiro Fujimoto, Takuya Matsuda, Manik Goyal, Jun Yoshinobu, Yohei Kobayashi, Takashi Oka, Susanne Stemmer, and Ryusuke Matsunaga

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Nano Letters
DOI: 10.1021/acs.nanolett.3c03770

[ASAP] Synchronizing Efficient Purification of VOCs in Durable Solar Water Evaporation over a Highly Stable Cu/W18O49@Graphene Material
Liteng Ren, Xiaonan Yang, Xin Sun, and Yupeng Yuan

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Nano Letters
DOI: 10.1021/acs.nanolett.3c04166

[ASAP] Free-Standing Carbon Nanotube Embroidered Graphene Film Electrode Array for Stable Neural Interfacing
Lei Gao, Suye Lv, Yuanyuan Shang, Shouliang Guan, Huihui Tian, Ying Fang, Jinfen Wang, and Hongbian Li

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Nano Letters
DOI: 10.1021/acs.nanolett.3c03421

[ASAP] Nanoscale Manipulation of Exciton–Trion Interconversion in a MoSe2 Monolayer via Tip-Enhanced Cavity-Spectroscopy
Mingu Kang, Su Jin Kim, Huitae Joo, Yeonjeong Koo, Hyeongwoo Lee, Hyun Seok Lee, Yung Doug Suh, and Kyoung-Duck Park

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Nano Letters
DOI: 10.1021/acs.nanolett.3c03920

[ASAP] Regulating Lewis Acidic Sites of 1T-2H MoS2 Catalysts for Solar-Driven Photothermal Catalytic H2 Production from Lignocellulosic Biomass
Chi Ma, Miao Cheng, Qing-Yu Liu, Yong-Jun Yuan, Fu-Guang Zhang, Naixu Li, Jie Guan, Zhi-Kai Shen, Zhen-Tao Yu, and Zhigang Zou

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Nano Letters
DOI: 10.1021/acs.nanolett.3c03947

[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

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

[ASAP] High-Performance Photodetectors Based on Semiconducting Graphene Nanoribbons
Mingyang Wang, Xiaoxiao Zheng, Xiaoling Ye, Wencheng Liu, Baoqing Zhang, Zihao Zhang, Rongli Zhai, Yafei Ning, Hu Li, and Aimin Song

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Nano Letters
DOI: 10.1021/acs.nanolett.3c03563

[ASAP] Nanoparticle Deep-Subwavelength Dynamics Empowered by Optical Meron–Antimeron Topology
Chengfeng Lu, Bo Wang, Xiang Fang, Din Ping Tsai, Weiming Zhu, Qinghua Song, Xiao Deng, Tao He, Xiaoyun Gong, Hong Luo, Zhanshan Wang, Xinhua Dai, Yuzhi Shi, and Xinbin Cheng

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Nano Letters
DOI: 10.1021/acs.nanolett.3c03351

Found 7 papers in acs-nano
Date of feed: Thu, 28 Dec 2023 22:22:51 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] Correction to “Multimodal E-Textile Enabled by One-Step Maskless Patterning of Femtosecond-Laser-Induced Graphene on Nonwoven, Knit, and Woven Textiles”
Dongwook Yang, Han Ku Nam, Truong-Son Dinh Le, Jinwook Yeo, Younggeun Lee, Young-Ryeul Kim, Seung-Woo Kim, Hak-Jong Choi, Hyung Cheoul Shim, Seunghwa Ryu, Soongeun Kwon, and Young-Jin Kim

ACS Nano
DOI: 10.1021/acsnano.3c09996

[ASAP] Crosstalk-Free Position Mapping for One-Step Reconstruction of Surface Topological Information via Eigenfrequency-Registered Wearable Interface
Dan Fang, Sen Ding, Qian Zhou, Dazhe Zhao, Junwen Zhong, and Bingpu Zhou

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ACS Nano
DOI: 10.1021/acsnano.3c11080

[ASAP] Synergetic Enhancement of Quantum Yield and Exciton Lifetime of Monolayer WS2 by Proximal Metal Plate and Negative Electric Bias
Trang Thu Tran, Yongjun Lee, Shrawan Roy, Thi Uyen Tran, Youngbum Kim, Takashi Taniguchi, Kenji Watanabe, Milorad V. Milošević, Seong Chu Lim, Andrey Chaves, Joon I. Jang, and Jeongyong Kim

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ACS Nano
DOI: 10.1021/acsnano.3c05667

[ASAP] Atomic Diffusion-Induced Polarization and Superconductivity in Topological Insulator-Based Heterostructures
Xian-Kui Wei, Abdur Rehman Jalil, Philipp Rüßmann, Yoichi Ando, Detlev Grützmacher, Stefan Blügel, and Joachim Mayer

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ACS Nano
DOI: 10.1021/acsnano.3c08601

[ASAP] Vertical Phase-Engineering MoS2 Nanosheet-Enhanced Textiles for Efficient Moisture-Based Energy Generation
Yuan-Ming Cao, Yang Su, Mi Zheng, Peng Luo, Yang-Biao Xue, Bin-Bin Han, Min Zheng, Zuoshan Wang, Liang-Sheng Liao, and Ming-Peng Zhuo

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ACS Nano
DOI: 10.1021/acsnano.3c08132

[ASAP] Topological Learning for the Classification of Disorder: An Application to the Design of Metasurfaces
Tristan Madeleine, Nina Podoliak, Oleksandr Buchnev, Ingrid Membrillo Solis, Tetiana Orlova, Maria van Rossem, Malgosia Kaczmarek, Giampaolo D’Alessandro, and Jacek Brodzki

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ACS Nano
DOI: 10.1021/acsnano.3c08776

[ASAP] Regulated Behavior in Living Cells with Highly Aligned Configurations on Nanowrinkled Graphene Oxide Substrates: Deep Learning Based on Interplay of Cellular Contact Guidance
Rowoon Park, Moon Sung Kang, Gyeonghwa Heo, Yong Cheol Shin, Dong-Wook Han, and Suck Won Hong

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ACS Nano
DOI: 10.1021/acsnano.2c09815