Found 36 papers in cond-mat
Date of feed: Thu, 29 Jun 2023 00:30:00 GMT

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Electrical contact properties between Yb and few-layer WS$_2$. (arXiv:2306.15689v1 [cond-mat.mtrl-sci])
Shihao Ju, Lipeng Qiu, Jian Zhou, Binxi Liang, Wenfeng Wang, Taotao Li, Jian Chen, Xinran Wang, Yi Shi, Songlin Li

Charge injection mechanism from contact electrodes into two-dimensional (2D) dichalcogenides is an essential topic for exploiting electronics based on 2D channels, but remains not well understood. Here, low-work-function metal ytterbium (Yb) was employed as contacts for tungsten disulfide (WS$_2$) to understand the realistic injection mechanism. The contact properties in WS$_2$ with variable temperature (T) and channel thickness (tch) were synergetically characterized. It is found that the Yb/WS$_2$ interfaces exhibit a strong pinning effect between energy levels and a low contact resistance ($R_\rm{C}$) value down to $5\,k\Omega\cdot\mu$m. Cryogenic electrical measurements reveal that $R_\rm{C}$ exhibits weakly positive dependence on T till 77 K, as well as a weakly negative correlation with tch. In contrast to the non-negligible $R_\rm{C}$ values extracted, an unexpectedly low effective thermal injection barrier of 36 meV is estimated, indicating the presence of significant tunneling injection in subthreshold regime and the inapplicability of the pure thermionic emission model to estimate the height of injection barrier.

A nanogapped hysteresis-free field-effect transistor. (arXiv:2306.15690v1 [cond-mat.mes-hall])
Jiachen Tang, Luhao Liu, Yinjiang Shao, Xinran Wang, Yi Shi, Songlin Li

We propose a semi-suspended device structure and construct nanogapped, hysteresis-free field-effect transistors (FETs), based on the van der Waals stacking technique. The structure, which features a semi-suspended channel above a submicron-long wedge-like nanogap, is fulfilled by transferring ultraclean BN-supported MoS$_2$ channels directly onto dielectric-spaced vertical source/drain stacks. Electronic characterization and analyses reveal a high overall device quality, including ultraclean channel interfaces, negligible electrical scanning hysteresis, and Ohmic contacts in the structures. The unique hollow FET structure holds the potential for exploiting reliable electronics, as well as nanofluid and pressure sensors.

Clean BN encapsulated 2D FETs with lithography compatible contacts. (arXiv:2306.15691v1 [cond-mat.mes-hall])
Binxi Liang, Anjian Wang, Jian Zhou, Shihao Ju, Jian Chen, Kenji Watanabe, Takashi Taniguchi, Yi Shi, Songlin Li

Device passivation through ultraclean hexagonal BN encapsulation is proven one of the most effective ways for constructing high-quality devices with atomically thin semiconductors that preserves the ultraclean interface quality and intrinsic charge transport behavior. However, it remains challenging to integrate lithography compatible contact electrodes with flexible distributions and patterns. Here, we report the feasibility in straightforwardly integrating lithography defined contacts into BN encapsulated 2D FETs, giving rise to overall device quality comparable to the state-of-the-art results from the painstaking pure dry transfer processing. Electronic characterization on FETs consisting of WSe$_2$ and MoS$_2$ channels reveals an extremely low scanning hysteresis of ca. 2 mV on average, a low density of interfacial charged impurity of ca. $10^{11}\,$cm$^{-2}$, and generally high charge mobilities over $1000\,$cm$^{2}\cdot$V$^{-1}\cdot$s$^{-1}$ at low temperatures. The overall high device qualities verify the viability in directly integrating lithography defined contacts into BN encapsulated devices to exploit their intrinsic charge transport properties for advanced electronics.

Spin-circuit representation of spin pumping into topological insulators and determination of giant spin Hall angle and inverse spin Hall voltages. (arXiv:2306.15699v1 [cond-mat.mes-hall])
Kuntal Roy

Topological insulators and giant spin-orbit toque switching of nanomagnets are one of the frontier topics for the development of energy-efficient spintronic devices. Spin-circuit representations involving different materials and phenomena are quite well-established now for its prowess of interpreting experimental results and then designing complex and efficient functional devices. Here, we construct the spin-circuit representation of spin pumping into topological insulators considering both the bulk and surface states with parallel channels, which allows the interpretation of practical experimental results. We show that the high increase in effective spin mixing conductance and inverse spin Hall voltages cannot be explained by the low-conductive bulk states of topological insulators. We determine high spin Hall angle close to the maximum magnitude of one from experimental results and with an eye to design efficient spin devices, we further employ a spin-sink layer in the spin-circuit formalism to increase the effective spin mixing conductance at low thicknesses and double the inverse spin Hall voltage.

Formation of droplets of the order parameter and superconductivity in inhomogeneous Fermi-Bose mixtures (Brief review). (arXiv:2306.15770v1 [cond-mat.mes-hall])
M.Yu. Kagan, S.V. Aksenov, A.V. Turlapov, R.Sh. Ikhsanov, K.I. Kugel, E.A. Mazur, E.A. Kuznetsov, V.M. Silkin, E.A. Burovski

The studies of a number of systems treated in terms of an inhomogeneous (spatially separated) Fermi-Bose mixture with superconducting clusters or droplets of the order parameter in a host medium with unpaired normal states are reviewed. A spatially separated Fermi-Bose mixture is relevant to superconducting BaKBiO3 bismuth oxides. Droplets of the order parameter can occur in thin films of a dirty metal, described in the framework of the strongly attractive two-dimensional Hubbard model at a low electron density with a clearly pronounced diagonal disorder. The Bose-Einstein condensate droplets are formed in mixtures and dipole gases with an imbalance in the densities of the Fermi and Bose components. The Bose-Einstein condensate clusters also arise at the center or at the periphery of a magnetic trap involving spin-polarized Fermi gases. Exciton and plasmon collapsing droplets can emerge in the presence of the exciton-exciton or plasmon-plasmon interaction. The plasmon contribution to the charge screening in MgB2 leads to the formation of spatially modulated inhomogeneous structures. In metallic hydrogen and metal hydrides, droplets can be formed in shock-wave experiments at the boundary of the first-order phase transition between the metallic and molecular phases. In a spatially separated Fermi-Bose mixture arising in an Aharonov-Bohm interference ring with a superconducting bridge in a topologically nontrivial state, additional Fano resonances may appear and collapse due to the presence of edge Majorana modes in the system.

Pressure dependence of intra- and interlayer excitons in 2H-MoS$_2$ bilayers. (arXiv:2306.15780v1 [cond-mat.mes-hall])
Paul Steeger, Jan-Hauke Graalmann, Robert Schmidt, Ilya Kupenko, Carmen Sanchez-Valle, Philipp Marauhn, Thorsten Deilmann, Steffen Michaelis de Vasconcellos, Michael Rohlfing, Rudolf Bratschitsch

The optical and electronic properties of multilayer transition metal dichalcogenides differ significantly from their monolayer counterparts due to interlayer interactions. The separation of individual layers can be tuned in a controlled way by applying pressure. Here, we use a diamond anvil cell to compress bilayers of 2H-MoS$_2$ in the gigapascal range. By measuring optical transmission spectra, we find that increasing pressure leads to a decrease in the energy splitting between the A and interlayer exciton. Comparing our experimental findings with ab initio calculations, we conclude that the observed changes are not due to the commonly assumed hydrostatic compression. This effect is attributed to the MoS$_2$ bilayer adhering to the diamond, which reduces in-plane compression. Moreover, we demonstrate that the distinct real-space distributions and resulting contributions from the valence band account for the different pressure dependencies of the inter- and intralayer excitons in compressed MoS$_2$ bilayers.

Kibble-Zurek mechanism of Ising domains. (arXiv:2306.15821v1 [cond-mat.stat-mech])
Kai Du, Xiaochen Fang, Choongjae Won, Chandan De, Fei-ting Huang Fernando J. Gomez-Ruiz, Adolfo Del Campo, Sang-Wook Cheong

The formation of topological defects after a symmetry-breaking phase transition is an overarching phenomenon that encodes rich information about the underlying dynamics. Kibble-Zurek mechanism (KZM), which describes these nonequilibrium dynamics, predicts defect densities of these second-order phase transitions driven by thermal fluctuations. It has been verified as a successful model in a wide variety of physical systems, finding applications from structure formation in the early universe to condensed matter systems. However, whether topologically-trivial Ising domains, one of the most common and fundamental types of domains in condensed matter systems, also obey the KZM has never been investigated in the laboratory. We examined two different kinds of three-dimensional (3D) structural Ising domains: clockwise (CW)/counter-clockwise (CCW) ferro-rotation domains in NiTiO3 and up/down polar domains in BiTeI. While the KZM slope of ferro-rotation domains in NiTiO3 agrees well with the prediction of the 3D Ising model, the KZM slope of polar domains in BiTeI surprisingly far exceeds the theoretical limit, setting an exotic example where possible weak long-range dipolar interactions play a critical role in steepening the KZM slope of non-topological quantities. Our results demonstrate the validity of KZM for Ising domains and reveal an enhancement of the power-law exponent and a possible reduction of the dynamic critical exponent z for transitions with long-range interactions.

Sterically Induced Binding Selectivity of Single m-Terphenyl Isocyanide Ligands. (arXiv:2306.15840v1 [cond-mat.mes-hall])
Liya Bi, Sasawat Jamnuch, Amanda Chen, Alexandria Do, Krista P. Balto, Zhe Wang, Qingyi Zhu, Yufei Wang, Yanning Zhang, Andrea R. Tao, Tod A. Pascal, Joshua S. Figueroa, Shaowei Li

Sterically encumbering m-terphenyl isocyanides are a class of metal-binding group that foster low-coordinate metal-center environments in coordination chemistry by exerting considerable intermolecular steric pressures between neighboring ligands. In the context of metal surfaces, the encumbering steric properties of the m-terphenyl isocyanides are shown to weaken the interaction between the metal-binding group and a planar substrate, leading to a preference for molecular adsorption at sites with convex curvature, such as the step edges and herringbone elbow sites on Au(111). Here, we investigate the site-selective binding of individual m-terphenyl isocyanide ligands on a Au(111) surface through scanning tunneling microscopy (STM) and inelastic electron tunneling spectroscopy (IETS). The site-dependent steric pressure alters the vibrational fingerprint of the m-terphenyl isocyanides, which is characterized with single-molecule precision through joint experimental and theoretical approaches. This study for the first time provides molecular-level insights into the steric-pressure-enabled surface binding selectivity as well as its effect on the chemical properties of individual m-terphenyl isocyanide ligands, thereby highlighting the potential to control the physical and chemical properties of metal surfaces through tailored ligand design.

Coupling and decoupling of bilayer graphene monitored by electron energy loss spectroscopy. (arXiv:2306.15849v1 [cond-mat.mtrl-sci])
Yung-Chang Lin, Amane Motoyama, Pablo Solis-Fernandez, Rika Matsumoto, Hiroki Ago, Kazu Suenaga

We studied the interlayer coupling and decoupling of bilayer graphene (BLG) by using spatially resolved electron energy loss spectroscopy (EELS) with a monochromated electron source. We correlated the twist-angle-dependent energy band hybridization with Moire superlattices and the corresponding optical absorption peaks. The optical absorption peak originates from the excitonic transition between the hybridized van Hove singularities (vHSs), which shifts systematically with the twist angle. We then proved that the BLG decouples when a monolayer of metal chloride is intercalated in its van der Waals (vdW) gap, and results in the elimination of the vHS peak.

Chern insulating state with double-$Q$ ordering wave vectors at the Brillouin zone boundary. (arXiv:2306.15854v1 [cond-mat.str-el])
Satoru Hayami

Magnetic multiple-$Q$ states consisting of multiple spin density waves are a source of unconventional topological spin textures, such as skyrmion and hedgehog. We theoretically investigate a topologically nontrivial double-$Q$ state with a net spin scalar chirality on a two-dimensional square lattice. We find that a double-$Q$ spiral superposition of the ordering wave vectors located at the Brillouin zone boundary gives rise to unconventional noncoplanar spin textures distinct from the skyrmion crystal. We show that such a double-$Q$ state is stabilized by the interplay among the easy-axis anisotropic interaction, high-harmonic wave-vector interaction, and external magnetic field. Furthermore, the obtained double-$Q$ state becomes a Chern insulating state with a quantum Hall conductivity when the Fermi level is located in the band gaps. Our present results provide another platform to realize topological magnetic states other than skyrmion crystals by focusing on the symmetry of constituent ordering wave vectors in momentum space.

Dissipative Spin-wave Diode and Nonreciprocal Magnonic Amplifier. (arXiv:2306.15916v1 [cond-mat.mes-hall])
Ji Zou, Stefano Bosco, Even Thingstad, Jelena Klinovaja, Daniel Loss

We propose an experimentally feasible dissipative spin-wave diode comprising two magnetic layers coupled via a non-magnetic spacer. We theoretically demonstrate that the spacer mediates not only coherent interactions but also dissipative coupling. Interestingly, an appropriately engineered dissipation engenders a nonreciprocal device response, facilitating the realization of a spin-wave diode. This diode permits wave propagation in one direction alone, given that the coherent Dzyaloshinskii- Moriya (DM) interaction is balanced with the dissipative coupling. The polarity of the diode is determined by the sign of the DM interaction. Furthermore, we show that when the magnetic layers undergo incoherent pumping, the device operates as a unidirectional spin-wave amplifier. The amplifier gain is augmented by cascading multiple magnetic bilayers. By extending our model to a one-dimensional ring structure, we establish a connection between the physics of spin-wave amplification and non-Hermitian topology. Our proposal opens up a new avenue for harnessing inherent dissipation in spintronic applications.

Dyck Paths and Topological Quantum Computation. (arXiv:2306.16062v1 [quant-ph])
Vivek Kumar Singh, Akash Sinha, Pramod Padmanabhan, Indrajit Jana

The fusion basis of Fibonacci anyons supports unitary braid representations that can be utilized for universal quantum computation. We show a mapping between the fusion basis of three Fibonacci anyons, $\{|1\rangle, |\tau\rangle\}$, and the two length 4 Dyck paths via an isomorphism between the two dimensional braid group representations on the fusion basis and the braid group representation built on the standard $(2,2)$ Young diagrams using the Jones construction. This correspondence helps us construct the fusion basis of the Fibonacci anyons using Dyck paths as the number of standard $(N,N)$ Young tableaux is the Catalan number, $C_N$ . We then use the local Fredkin moves to construct a spin chain that contains precisely those Dyck paths that correspond to the Fibonacci fusion basis, as a degenerate set. We show that the system is gapped and examine its stability to random noise thereby establishing its usefulness as a platform for topological quantum computation. Finally, we show braidwords in this rotated space that efficiently enable the execution of any desired single-qubit operation, achieving the desired level of precision($\sim 10^{-3}$).

MoRe Electrodes with 10-nm Nanogaps for Electrical Contact to Atomically Precise Graphene Nanoribbons. (arXiv:2306.16070v1 [cond-mat.mes-hall])
Damian Bouwmeester, Talieh S. Ghiasi, Gabriela Borin Barin, Klaus Müllen, Pascal Ruffieux, Roman Fasel, Herre S.J. van der Zant

Atomically precise graphene nanoribbons (GNRs) are predicted to exhibit exceptional edge-related properties, such as localized edge states, spin polarization, and half-metallicity. However, the absence of low-resistance nano-scale electrical contacts to the GNRs hinders harnessing their properties in field-effect transistors. In this paper, we make electrical contact with 9-atom-wide armchair GNRs using superconducting alloy MoRe as well as Pd (as a reference), which are two of the metals providing low-resistance contacts to carbon nanotubes. We take a step towards contacting a single GNR by fabrication of electrodes with a needle-like geometry, with about 20 nm tip diameter and 10 nm separation. To preserve the nano-scale geometry of the contacts, we develop a PMMA-assisted technique to transfer the GNRs onto the pre-patterned electrodes. Our device characterizations as a function of bias-voltage and temperature, show a thermally-activated gate-tunable conductance in the GNR-MoRe-based transistors.

Spin-resolved spectroscopic evidence for spinarons in Co adatoms. (arXiv:2306.16084v1 [cond-mat.str-el])
Felix Friedrich, Artem Odobesko, Juba Bouaziz, Samir Lounis, Matthias Bode

Single cobalt atoms on the (111) surfaces of noble metals were for a long time considered prototypical systems for the Kondo effect in scanning tunneling microscopy experiments. Yet, recent first-principle calculations suggest that the experimentally observed spectroscopic zero-bias anomaly (ZBA) should be interpreted in terms of excitations of the Co atom's spin and the formation of a novel quasiparticle, the spinaron, a magnetic polaron resulting from the interaction of spin excitations with conduction electrons, rather than in terms of a Kondo resonance. Here we present state-of-the-art spin-averaged and spin-polarized scanning tunneling spectroscopy measurements on Co atoms on the Cu(111) surface in magnetic fields of up to 12 T, that allow us to discriminate between the different theoretical models and to invalidate the prevailing Kondo-based interpretation of the ZBA. Employing extended ab-initio calculations, we instead provide strong evidence for multiple spinaronic states in the system. Our work opens a new avenue of research to explore the characteristics and consequences of these intriguing hybrid many-body states as well as their design in man-made nanostructures.

Strong coupling of monolayer WS2 excitons and surface plasmon polaritons in a planar Ag/WS2 hybrid structure. (arXiv:2306.16107v1 [physics.optics])
Nicolas Zorn Morales, Daniel Steffen Rühl, Sergey Sadofev, Giovanni Ligorio, Emil List-Kratochvil, Günter Kewes, Sylke Blumstengel

Monolayer (1L) transition metal dichalcogenides (TMDC) are of strong interest in nanophotonics due to their narrow-band intense excitonic transitions persisting up to room temperature. When brought into resonance with surface plasmon polariton (SPP) excitations of a conductive medium opportunities for studying and engineering strong light-matter coupling arise. Here, we consider a most simple geometry, namely a planar stack composed of a thin silver film, an Al2O3 spacer and a monolayer of WS2. We perform total internal reflection ellipsometry which combines spectroscopic ellipsometry with the Kretschmann-Raether-type surface plasmon resonance configuration. The combined amplitude and phase response of the reflected light at varied angle of incidence proves that despite the atomic thinness of 1L-WS2, the strong coupling (SC) regime between A excitons and SPPs propagating in the thin Ag film is reached. The phasor representation of rho corroborates SC as rho undergoes a topology change indicated by the occurrence of a double point at the cross over from the weak to the strong coupling regime. Our findings are validated by both analytical transfer matrix method calculations and numerical Maxwell simulations. The findings open up new perspectives for applications in plasmonic modulators and sensors benefitting from the tunability of the optical properties of 1L-TMDCs by electric fields, electrostatic doping, light and the chemical environment.

Quantum-information theory of magnetic field influence on circular dots with different boundary conditions. (arXiv:2306.16114v1 [quant-ph])
H. Shafeekali, O. Olendski

Influence of the transverse uniform magnetic field $\bf B$ on position (subscript $\rho$) and momentum ($\gamma$) Shannon quantum-information entropies $S_{\rho,\gamma}$, Fisher informations $I_{\rho,\gamma}$ and informational energies $O_{\rho,\gamma}$ is studied theoretically for the 2D circular quantum dots (QDs) whose circumference supports homogeneous either Dirichlet or Neumann boundary condition (BC). Analysis reveals similarities and differences of the influence on the properties of the structure of the surface interaction with the magnetic field. Conspicuous distinction between the spectra are crossings at the increasing induction of the Neumann energies with the same radial quantum number $n$ and adjacent non-positive angular indices $m$. At the growing $B$, either system undergoes Landau condensation when its characteristics turn into their uniform field counterparts. For the Dirichlet system this transformation takes place at the smaller magnetic intensities; e.g., the Dirichlet sum $S_{\rho_{00}}+S_{\gamma_{00}}$ on its approach from above to a fundamental limit $2(1+\ln\pi)$ is at any $B$ smaller than the corresponding Neumann quantity what physically means that the former geometry provides more total information about the position and motion of the particle. It is pointed out that the widely accepted disequilibrium uncertainty relation $O_\rho O_\gamma\leq(2\pi)^{-\mathtt{d}}$, with $\mathtt{d}$ being a dimensionality of the system, is violated by the Neumann QD in the magnetic field. Comparison with electrostatic harmonic confinement is performed. Physical interpretation is based on the different roles of the two BCs and their interplay with the field: Dirichlet (Neumann) surface is a repulsive (attractive) interface.

Accurate force-field methodology capturing atomic reconstructions in transition metal dichalcogenide moir\'e systems. (arXiv:2306.16124v1 [cond-mat.mtrl-sci])
Carl Emil Mørch Nielsen, Miguel da Cruz, Abderrazak Torche, Gabriel Bester

In this work, a generalized force-field methodology for the relaxation of large moir\'e heterostructures is proposed. The force-field parameters are optimized to accurately reproduce the structural degrees of freedom of some computationally manageable cells relaxed using density functional theory. The parameters can then be used to handle large moir\'e systems. We specialize to the case of 2H-phased twisted transition-metal dichalcogenide homo- and heterobilayers using a combination of the Stillinger-Weber intralayer- and the Kolmogorov-Crespi interlayer-potential. Force-field parameters are developed for all combinations of MX$_2$ for $\text{M}\in\{\text{Mo},\text{W}\}$ and $\text{X}\in\{\text{S},\text{Se},\text{Te}\}$. The results show agreement within 20 meV in terms of band structure between density functional theory and force-field relaxation. Using the relaxed structures, a simplified and systematic scheme for the extraction of the interlayer moir\'e potential is presented for both R- and H-stacked systems. We show that in-plane and out-of-plane relaxation effects on the moir\'e potential, which is made both deeper and wider after relaxation, are essential. An interpolation based methodology for the calculation of the interlayer binding energy is also proposed. Finally, we show that atomic reconstruction, which is captured by the force-field method, becomes especially prominent for angles below 4-5$^\circ$, when there is no mismatch in lattice constant between layers.

Phase diagram of the chiral SU(3) antiferromagnet on the kagome lattice. (arXiv:2306.16192v1 [cond-mat.str-el])
Yi Xu, Sylvain Capponi, Ji-Yao Chen, Laurens Vanderstraeten, Juraj Hasik, Andriy H. Nevidomskyy, Matthieu Mambrini, Karlo Penc, Didier Poilblanc

Motivated by the search for chiral spin liquids (CSL), we consider a simple model defined on the kagome lattice of interacting SU(3) spins (in the fundamental representation) including two-site and three-site permutations between nearest neighbor sites and on triangles, respectively. By combining analytical developments and various numerical techniques, namely exact Lanczos diagonalizations and tensor network variational approaches, we find a rich phase diagram with non-topological (``trivial") and topological (possibly chiral) gapped spin liquids (SLs). Trivial spin liquids include an Affleck-Kennedy-Lieb-Tasaki (AKLT)-like phase and a trimerized phase, the latter breaking the inversion center between the up and down triangles of the kagome lattice. A topological SL is stabilized in a restricted part of the phase diagram by the time-reversal symmetry breaking (complex) 3-site permutation term. Analyzing the chiral edge modes of this topological SL on long cylinders or on finite disks, we have come up with two competing scenarios, either a CSL or a double Chern-Simon SL characterized by a single or by two counter-propagating Wess-Zumino-Witten SU(3)$_1$ chiral mode(s), respectively. In the vicinity of the extended ferromagnetic region we have found a magnetic phase corresponding either to a modulated canted ferromagnet or to a uniform partially magnetized ferromagnet.

Non-local transport signatures of topological superconductivity in a phase-biased planar Josephson junction. (arXiv:2306.16232v1 [cond-mat.mes-hall])
D. Kuiri, M. P. Nowak

Hybrid Josephson junctions realized on a two-dimensional electron gas are considered promising candidates for developing topological elements that are easily controllable and scalable. Here, we theoretically study the possibility of the detection of topological superconductivity via the non-local spectroscopy technique. We show that the non-local conductance is related to the system band structure, allowing probe of the gap closing and reopening related to the topological transition. We demonstrate that the topological transition induces a change in the sign of the non-local conductance at zero energy due to the change in the quasiparticle character of the dispersion at zero momentum. Importantly, we find that the tunability of the superconducting phase difference via flux in hybrid Josephson junctions systems is strongly influenced by the strength of the Zeeman interaction, which leads to considerable modifications in the complete phase diagram that can be measured under realistic experimental conditions.

The dynamical structure factor of the SU(4) algebraic spin liquid on the honeycomb lattice. (arXiv:2306.16242v1 [cond-mat.str-el])
Dániel Vörös, Karlo Penc

We compute the momentum resolved dynamical spin structure factor $S(k,\omega)$ of the SU(4) Heisenberg model on the honeycomb lattice assuming the $\pi$-flux Dirac spin liquid ground state by two methods: (i) variationally using Gutzwiller projected particle-hole excitations of the $\pi$-flux Fermi sea and (ii) in the non-interacting parton mean-field picture. The two approaches produce qualitatively similar results. Based on this analogy, we argue that the energy spectrum of the projected excitations is a gapless continuum of fractional excitations. Quantitatively, the Gutzwiller projection shifts the weight from higher to lower energies, thus emphasizing the lower edge of the continuum. In the mean-field approach, we obtained the $1/\text{distance}^4$ decay of the spin correlation function, and the local correlations show $S^{33}_{\text{MF}}(\omega)\propto \omega^3$ behavior.

Roadmap towards Majorana qubits and nonabelian physics in quantum dot-based minimal Kitaev chains. (arXiv:2306.16289v1 [cond-mat.mes-hall])
Athanasios Tsintzis, Rubén Seoane Souto, Karsten Flensberg, Jeroen Danon, Martin Leijnse

The possibility to engineer artificial Kitaev chains in arrays of quantum dots coupled via narrow superconducting regions has emerged as an attractive way to overcome the disorder issues that complicate the realization and detection of topological superconducting phases in other platforms. Although a true topological phase would require long chains, already a two-site chain realized in a double quantum dot can be tuned to points in parameter space where it hosts zero-energy states that seem identical to the Majorana bound states that characterize a topological phase. These states were named "poor man's Majorana bound states" (PMMs) because they lack formal topological protection. In this work, we propose a roadmap for next-generation experiments on PMMs. The roadmap starts with experiments to characterize a single pair of PMMs by measuring the Majorana quality, then moves on to initialization and readout of the parity of a PMM pair, which allows measuring quasiparticle poisoning times. The next step is to couple two PMM systems to form a qubit. We discuss measurements of the coherence time of such a qubit, as well as a test of Majorana fusion rules in the same setup. Finally, we propose and analyse three different types of braiding-like experiments which require more complex device geometries. Our conclusions are supported by calculations based on a realistic model with interacting and spinful quantum dots, as well as by simpler models to gain physical insight. Our calculations show that it is indeed possible to demonstrate nonabelian physics in minimal two-site Kitaev chains despite the lack of a true topological phase. But our findings also reveal that doing so requires some extra care, appropriately modified protocols and awareness of the details of this particular platform.

Electronic Landscape of Kagome Superconductors $\textit{A}$V$_{3}$Sb$_{5}$ ($\textit{A}$ = K, Rb, Cs): A Perspective from Angle-Resolved Photoemission Spectroscopy. (arXiv:2306.16343v1 [cond-mat.supr-con])
Yong Hu, Xianxin Wu, Andreas P. Schnyder, Ming Shi

The recently discovered layered kagome superconductors $\textit{A}$V$_{3}$Sb$_{5}$ ($\textit{A}$ = K, Rb, Cs) have garnered significant attention, as they exhibit an intriguing combination of superconductivity, charge density wave (CDW) order, and nontrivial band topology. As such, these kagome systems serve as an exceptional quantum platform for investigating the intricate interplay between electron correlation effects, geometric frustration, and topological electronic structure. A comprehensive understanding of the underlying electronic structure is crucial for unveiling the nature and origin of the CDW order, as well as determining the electron pairing symmetry in the kagome superconductors. In this review, we present a concise survey of the electronic properties of $\textit{A}$V$_{3}$Sb$_{5}$, with a particular focus on the insights derived from angle-resolved photoemission spectroscopy (ARPES). Through the lens of ARPES, we shed light on the electronic characteristics of the kagome superconductors $\textit{A}$V$_{3}$Sb$_{5}$, which will pave the way for exciting new research frontiers in kagome-related physics.

Dirac materials in parallel non-uniform electromagnetic fields generated by SUSY: A new class of chiral Planar Hall Effect?. (arXiv:2306.16399v1 [hep-th])
Julio Cesar Pérez-Pedraza, Juan D. García-Muñoz, A. Raya

Within a Supersymmetric Quantum Mechanics (SUSY-QM) framework, the (3+1) Dirac equation describing a Dirac material in the presence of external parallel electric and magnetic fields is solved. Considering static but non-uniform electric and magnetic profiles with translational symmetry along the y-direction, the Dirac equation is transformed into two decoupled pairs of Schr\"odinger equations, one for each chirality of the fermion fields. Taking trigonometric and hyperbolic profiles for the vector and scalar potentials, respectively, we arrive at SUSY partner P\"oschl-Teller-like quantum potentials. Restricting to the conditions of the potentials that support an analytic zero-mode solution, we obtain a nontrivial current density in the same plane where the electric and magnetic fields lie, but perpendicular to both of them, indicating the possibility of realizing the Planar Hall Effect. Furthermore, this non-vanishing current density is the sum of current densities for the left- and right-chiralities, suggesting that the net current is a consequence of chiral symmetry.

Pumping with Symmetry. (arXiv:2306.16401v1 [cond-mat.mtrl-sci])
Julio Andrés Iglesias Martínez, Muamer Kadic, Vincent Laude, Emil Prodan

Re-configurable materials and meta-materials can jump between space symmetry classes during their deformations. Here, we introduce the concept of singular symmetry enhancement, which refers to an abrupt jump to a higher symmetry class accompanied by an un-avoidable reduction in the number of dispersion bands of the excitations of the material. Such phenomenon prompts closings of some of the spectral resonant gaps along singular manifolds in a parameter space. In this work, we demonstrate that these singular manifolds carry topological charges. As a concrete example, we show that a deformation of an acoustic crystal that encircles a $p11g$-symmetric configuration of the cavity resonators results in an adiabatic cycle that carries a Chern number in the bulk and displays Thouless pumping at the edges. The outcome is a very general principle for recognizing or engineering topological adiabatic processes in complex materials and meta-materials.

Third-order Hall effect in the surface states of a topological insulator. (arXiv:2209.06867v2 [cond-mat.mes-hall] UPDATED)
Tanay Nag, Sanjib Kumar Das, Chuanchang Zeng, Snehasish Nandy

Time reversal and inversion symmetric materials fail to yield linear and nonlinear responses since they possess net zero Berry curvature. However, higher-order Hall response can be generated in these systems upon constraining the crystalline symmetries. Motivated by the recently discovered third-order Hall (TOH) response mediated by Berry connection polarizability, namely, the variation the Berry connection with respect to an applied electric field, here we investigate the existence of such Hall effect in the surface states of hexagonal warped topological insulator (e.g., Bi$_2$Te$_3$) under the application of electric field only. Using the semiclassical Boltzmann formalism, we investigate the effect of tilt and hexagonal warping on the Berry connection polarizability tensor and consequently, the TOH effect provided the Dirac cone remains gapless. We find that the magnitude of the response increases significantly with increasing the tilt strength and warping and therefore, they can provide the tunability of this effect. In addition, we also explore the effect of chemical doping on TOH response in this system. Interestingly, we show based on the symmetry analysis, that the TOH can be the leading-order response in this system which can directly be verified in experiments.

1/4 is the new 1/2: Interaction-induced Unification of Quantum Anomalous and Spin Hall Effects. (arXiv:2210.11486v4 [cond-mat.mes-hall] UPDATED)
Peizhi Mai, Jinchao Zhao, Benjamin E. Feldman, Philip W. Phillips

We introduce interactions into two general models for quantum spin Hall physics. Although the traditional picture is that such physics appears when the two lower spinful bands are occupied, that is, half-filling, we show using determinantal quantum Monte Carlo as well as from an exactly solvable model that in the presence of strong interactions, the quarter-filled state instead exhibits the quantum spin Hall effect at high temperature. A topological Mott insulator is the underlying cause. The peak in the spin susceptibility is consistent with a possible ferromagnetic state at $T=0$. The onset of such magnetism would convert the quantum spin Hall to a quantum anomalous Hall effect. We argue that it is the consistency with the Lieb-Schultz-Mattis theorem\cite{lsm1,lsm2} for interacting systems with an odd number of charges per unit cell that underlies the emergence of the quantum anomalous Hall effect as a low-temperature symmetry-broken phase of the quantum spin Hall effect. While such a symmetry-broken phase typically is accompanied by a gap, we find that the interaction strength must exceed a critical value for the gap to form using quantum Monte Carlo dynamical cluster approximation simulations. Hence, we predict that topology can obtain in a gapless phase but only in the presence of interactions in dispersive bands. These results are applied to recent experiments on moir\'e systems and shown to be consistent with valley-coherent quantum anomalous Hall physics.

Engineering and probing non-Abelian chiral spin liquids using periodically driven ultracold atoms. (arXiv:2211.09777v3 [cond-mat.quant-gas] UPDATED)
Bo-Ye Sun, Nathan Goldman, Monika Aidelsburger, Marin Bukov

We propose a scheme to implement Kitaev's honeycomb model with cold atoms, based on a periodic (Floquet) drive, in view of realizing and probing non-Abelian chiral spin liquids using quantum simulators. We derive the effective Hamiltonian to leading order in the inverse-frequency expansion, and show that the drive opens up a topological gap in the spectrum without mixing the effective Majorana and vortex degrees of freedom. We address the challenge of probing the physics of Majorana fermions, while having only access to the original composite spin degrees of freedom. Specifically, we propose to detect the properties of the chiral spin liquid phase using gap spectroscopy and edge quenches in the presence of the Floquet drive. The resulting chiral edge signal, which relates to the thermal Hall effect associated with neutral Majorana currents, is found to be robust for realistically-prepared states. By combining strong interactions with Floquet engineering, our work paves the way for future studies of non-Abelian excitations and quantized thermal transport using quantum simulators.

Realistic Spin Model for Multiferroic NiI$_2$. (arXiv:2211.14416v3 [cond-mat.str-el] UPDATED)
Xuanyi Li, Changsong Xu, Boyu Liu, Xueyang Li, L. Bellaiche, Hongjun Xiang

A realistic first-principle-based spin Hamiltonian is constructed for the type-II multiferroic NiI$_2$, using a symmetry-adapted cluster expansion method. Besides single ion anisotropy and isotropic Heisenberg terms, this model further includes the Kitaev interaction and a biquadratic term, and can well reproduce striking features of the experimental helical ground state, that are, {\it e.g.}, a proper screw state, canting of rotation plane, propagation direction and period. Using this model to build a phase diagram, it is demonstrated that, (i) the in-plane propagation direction of $\langle1\bar10\rangle$ is determined by the Kitaev interaction, instead of the long-believed exchange frustrations; and (ii) the canting of rotation plane is also dominantly determined by Kitaev interaction, rather than interlayer couplings. Furthermore, additional Monte Carlo simulations reveal three equivalent domains and different topological defects. Since the ferroelectricity is induced by spins in type-II multiferroics, our work also implies that Kitaev interaction is closely related to the multiferroicity of NiI$_2$.

Orbital-selective Mott phase and spin nematicity in Ni-substituted FeTe$_{0.65}$Se$_{0.35}$ single crystals. (arXiv:2211.15189v2 [cond-mat.supr-con] UPDATED)
Marta Z. Cieplak, I. Zajcewa, A. Lynnyk, K. M. Kosyl, D. J. Gawryluk

The normal state in iron chalcogenides is metallic but highly unusual, with orbital and spin degrees of freedom partially itinerant or localized depending on temperature, leading to many unusual features. In this work, we report on the observations of two of such features, the orbital selective Mott phase (OSMP) and spin nematicity, evidenced in magnetization and magnetotransport [resistivity, Hall effect, angular magnetoresistance (AMR)] of Fe$_{1-y}$Ni$_y$Te$_{0.65}$Se$_{0.35}$ single crystals, with $0 < y < 0.21$. Substitution of Ni dopes crystals with electrons, what eliminates some of the hole pockets from Fermi level, leaving only one, originating from $d_{xy}$ orbital. This leads to electron-dominated conduction at low $T$ for $y \gtrsim 0.06$. However, at high temperatures, $T \gtrsim 125 \div 178$ K, the conduction reverses to hole-dominated. Anomalies in magnetization and resistivity are observed at temperatures which approach high-$T$ boundary of the electron-dominated region. Analysis of these effects suggests a link with the appearance of the $d_{z^2}$ hole pockets at X points of the Brillouin zone in the OSMP phase, facilitated by the localization of $d_{xy}$ orbital, as recently reported by angular resolved photoemission experiments (Commun. Phys. 5, 29 (2022)). The low-$T$ AMR shows mixed 4-fold and 2-fold rotational symmetry of in-plane magnetocrystalline anisotropy, with the 4-fold term the largest at small $y$, and suppressed at intermediate $y$. These results are consistent with the mixed stripe/bicollinear magnetic correlations at small $y$, and suppression of stripe correlations at intermediate $y$, indicating development of spin nematicity with increasing Ni doping, which possibly contributes to the suppression of superconductivity.

Fermion disorder operator at Gross-Neveu and deconfined quantum criticalities. (arXiv:2212.11821v2 [cond-mat.str-el] UPDATED)
Zi Hong Liu, Weilun Jiang, Bin-Bin Chen, Junchen Rong, Meng Cheng, Kai Sun, Zi Yang Meng, Fakher F. Assaad

The fermion disorder operator has been shown to reveal the entanglement information in 1D Luttinger liquids and 2D free and interacting Fermi and non-Fermi liquids emerging at quantum critical points(QCP). Here we study, by means of large-scale quantum Monte Carlo simulation, the scaling behavior of disorder operator in correlated Dirac systems. We first demonstrate the logarithmic scaling behavior of the disorder operator at the Gross-Neveu (GN) chiral Ising and Heisenberg QCPs, where consistent conformal field theory (CFT) content of the GN-QCP in its coefficient is found. Then we study a 2D monopole free deconfined quantum critical point (DQCP) realized between a quantum-spin Hall insulator and a superconductor. Our data point to negative values of the logarithmic coefficients such that the DQCP does not correspond to a unitary CFT. Density matrix renormalization group calculations of the disorder operator on a 1D DQCP model also detect emergent continuous symmetries.

Nonlocality and entanglement in measured critical quantum Ising chains. (arXiv:2301.08268v2 [cond-mat.stat-mech] UPDATED)
Zack Weinstein, Rohith Sajith, Ehud Altman, Samuel J. Garratt

We study the effects of measurements, performed with a finite density in space, on the ground state of the one-dimensional transverse-field Ising model at criticality. Local degrees of freedom in critical states exhibit long-range entanglement, and as a result, local measurements can have highly nonlocal effects. Our analytical investigation of correlations and entanglement in the ensemble of measured states is based on properties of the Ising conformal field theory (CFT), where measurements appear as (1+0)-dimensional defects in the (1+1)-dimensional Euclidean spacetime. So that we can verify our predictions using large-scale free-fermion numerics, we restrict ourselves to parity-symmetric measurements. To describe their averaged effects analytically we use a replica approach, and we show that the defect arising in the replica theory is an irrelevant perturbation to the Ising CFT. Strikingly, the asymptotic scalings of averaged correlations and entanglement entropy are therefore unchanged relative to the ground state. In contrast, the defect generated by postselecting on the most likely measurement outcomes is exactly marginal. We then find that the exponent governing postmeasurement order parameter correlations, as well as the ''effective central charge'' governing the scaling of entanglement entropy, vary continuously with the density of measurements in space. Our work establishes new connections between the effects of measurements on many-body quantum states and of physical defects on low-energy equilibrium properties.

Orientational dynamics and rheology of active suspensions in weakly viscoelastic flows. (arXiv:2303.15241v2 [cond-mat.soft] UPDATED)
Akash Choudhary, Sankalp Nambiar, Holger Stark

Microswimmer suspensions in Newtonian fluids exhibit unusual macroscale properties, such as a superfluidic behavior, which can be harnessed to perform work at microscopic scales. Since most biological fluids are non-Newtonian, here we study the rheology of a microswimmer suspension in a weakly viscoelastic shear flow. At the individual level, we find that the viscoelastic stresses generated by activity substantially modify the Jeffery orbits well-known from Newtonian fluids. The orientational dynamics depends on the swimmer type; especially pushers can resist flow-induced rotation and align at an angle with the flow. To analyze its impact on bulk rheology, we study a dilute microswimmer suspension in the presence of random tumbling and rotational diffusion. Strikingly, swimmer activity and its elastic response in polymeric fluids alter the orientational distribution and substantially amplify the swimmer-induced viscosity. This suggests that pusher suspensions reach the superfluidic regime at lower volume fractions compared to a Newtonian fluid with identical viscosity.

Effects of first- and second-order topological phases on equilibrium crystal shapes. (arXiv:2304.08150v2 [cond-mat.mes-hall] UPDATED)
Yutaro Tanaka, Shuichi Murakami

We study equilibrium crystal shapes of a topological insulator (TI), a topological crystalline insulator (TCI) protected by mirror symmetry, and a second-order topological insulator (SOTI) protected by inversion symmetry. By adding magnetic fields to the three-dimensional TI, we can realize the mirror-symmetry-protected TCI and the inversion-symmetry-protected SOTI. They each have topological boundary states in different positions: the TCI has gapless states on the surfaces that are invariant under the symmetry operation, and the SOTI has gapless states at the intersections between certain surfaces. In this paper, we discuss how these boundary states affect the surface energies and the equilibrium crystal shapes in terms of the calculations of the simple tight-binding model by using the Wulff construction. By comparing the changes in the shapes of the TI to that of the trivial insulator through the process of applying the magnetic fields, we show that the presence/absence of the topological boundary states affects the emergence of the specific facets in a different way from the trivial insulator.

Charge-Density Waves vs. Superconductivity: Some Results and Future Perspectives. (arXiv:2305.03404v2 [cond-mat.supr-con] UPDATED)
Giulia Venditti, Sergio Caprara

Increasing experimental evidence suggests the occurrence of filamentary superconductivity in different (quasi) two-dimensional physical systems. In this piece of work, we discuss the proposal that under certain circumstances, this occurrence may be related to the competition with a phase characterized by charge ordering in the form of charge-density waves. We provide a brief summary of experimental evidence supporting our argument in two paradigmatic classes of materials, namely transition metal dichalcogenides and cuprates superconductors. We present a simple Ginzburg-Landau two-order-parameters model as a starting point to address the study of such competition. We finally discuss the outcomes of a more sophisticated model, already presented in the literature and encoding the presence of impurities, and how it can be further improved in order to really address the interplay between charge-density waves and superconductivity and the possible occurrence of filamentary superconductivity at the domain walls between different charge-ordered regions.

Ferroelectric and anomalous quantum Hall states in bare rhombohedral trilayer graphene. (arXiv:2305.04950v2 [cond-mat.mes-hall] UPDATED)
Felix Winterer, Fabian R. Geisenhof, Noelia Fernandez, Anna M. Seiler, Fan Zhang, R. Thomas Weitz

Nontrivial interacting phases can emerge in elementary materials. As a prime example, continuing advances in device quality have facilitated the observation of a variety of spontaneous quantum Hall-like states, a cascade of Stoner-like magnets, and an unconventional superconductor in bilayer graphene. Its natural extension, rhombohedral trilayer graphene is predicted to be even more susceptible to interactions given its even flatter low-energy bands and larger winding number. Theoretically, five spontaneous quantum Hall phases have been proposed to be candidate ground states. Here, we provide transport evidence for observing four of the five competing ordered states in interaction-maximized, dually-gated, rhombohedral trilayer graphene. In particular, at vanishing but finite magnetic fields, two states with Chern numbers 3 and 6 can be stabilized at elevated and low electric fields, respectively, and both exhibit clear magnetic hysteresis. We also reveal that the quantum Hall ferromagnets of the zeroth Landau level are ferroelectrics with spontaneous layer polarizations even at zero electric field, as evidenced by electric hysteresis. Our findings exemplify the possible birth of rich interacting electron physics in a simple elementary material.

Axion Insulator State in Hundred-Nanometer-Thick Magnetic Topological Insulator Sandwich Heterostructures. (arXiv:2306.13016v3 [cond-mat.mes-hall] UPDATED)
Deyi Zhuo, Zi-Jie Yan, Zi-Ting Sun, Ling-Jie Zhou, Yi-Fan Zhao, Ruoxi Zhang, Ruobing Mei, Hemian Yi, Ke Wang, Moses H. W. Chan, Chao-Xing Liu, K. T. Law, Cui-Zu Chang

An axion insulator is a three-dimensional (3D) topological insulator (TI), in which the bulk maintains the time-reversal symmetry or inversion symmetry but the surface states are gapped by surface magnetization. The axion insulator state has been observed in molecular beam epitaxy (MBE)-grown magnetically doped TI sandwiches and exfoliated intrinsic magnetic TI MnBi2Te4 flakes with an even number layer. All these samples have a thickness of ~10 nm, near the 2D-to-3D boundary. The coupling between the top and bottom surface states in thin samples may hinder the observation of quantized topological magnetoelectric response. Here, we employ MBE to synthesize magnetic TI sandwich heterostructures and find that the axion insulator state persists in a 3D sample with a thickness of ~106 nm. Our transport results show that the axion insulator state starts to emerge when the thickness of the middle undoped TI layer is greater than ~3 nm. The 3D hundred-nanometer-thick axion insulator provides a promising platform for the exploration of the topological magnetoelectric effect and other emergent magnetic topological states, such as the high-order TI phase.

Found 8 papers in prb
Date of feed: Thu, 29 Jun 2023 03:16:57 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]+)

Ferromagnetism and metal-insulator transition in F-doped ${\mathrm{LaMnO}}_{3}$
Ekta Yadav, Pramod Ghising, K. P. Rajeev, and Z. Hossain
Author(s): Ekta Yadav, Pramod Ghising, K. P. Rajeev, and Z. Hossain

We present our studies on polycrystalline samples of fluorine doped ${\mathrm{LaMnO}}_{3}$ (${\mathrm{LaMnO}}_{3−y}{\mathrm{F}}_{y}$). ${\mathrm{LaMnO}}_{3−y}{\mathrm{F}}_{y}$ exhibits remarkable magnetic and electrical properties. It shows ferromagnetic and metallic behavior with a high Curie tempe…

[Phys. Rev. B 107, 214446] Published Wed Jun 28, 2023

Weak localization and antilocalization in twisted bilayer graphene
Hongyi Yan and Haiwen Liu
Author(s): Hongyi Yan and Haiwen Liu

In this study, we investigate the weak localization (WL) and weak antilocalization (WAL) effects in twisted bilayer graphene positioned on a hexagonal boron nitride substrate. The bottom graphene layer aligns with the hexagonal boron nitride. The top layer of the system features a Dirac cone with a …

[Phys. Rev. B 107, 224205] Published Wed Jun 28, 2023

Impact of random impurities on the anomalous Hall effect in chiral superconductors
Hao-Tian Liu, Weipeng Chen, and Wen Huang
Author(s): Hao-Tian Liu, Weipeng Chen, and Wen Huang

The anomalous Hall effect and the closely related polar Kerr effect are among the most direct evidence of chiral Cooper pairing in some superconductors. While it has been known that disorder or multiband pairing is typically needed for these effects to manifest, there is a lack of direct real-space …

[Phys. Rev. B 107, 224517] Published Wed Jun 28, 2023

Robust high-temperature topological excitonic insulator of transition-metal carbide MXenes
Shan Dong and Yuanchang Li
Author(s): Shan Dong and Yuanchang Li

Topological excitonic insulators combine topological edge states and spontaneous exciton condensation, with dual functionality of topological insulators and excitonic insulators. Yet, they are very rare and little is known about their formation. In this work, we find that a mechanism dubbed as parit…

[Phys. Rev. B 107, 235147] Published Wed Jun 28, 2023

Transport in a periodically driven tilted lattice via the extended reservoir approach: Stability criterion for recovering the continuum limit
Bitan De, Gabriela Wójtowicz, Jakub Zakrzewski, Michael Zwolak, and Marek M. Rams
Author(s): Bitan De, Gabriela Wójtowicz, Jakub Zakrzewski, Michael Zwolak, and Marek M. Rams

Extended reservoirs provide a framework for capturing macroscopic, continuum environments, such as metallic electrodes driving a current through a nanoscale contact, impurity, or material. We examine the application of this approach to periodically driven systems, specifically in the context of quan…

[Phys. Rev. B 107, 235148] Published Wed Jun 28, 2023

Ultrafast carrier dynamics and symmetry reduction in bismuth by nonperturbative optical excitation in the terahertz range
Matthias Runge, Ahmed Ghalgaoui, Isabel Gonzalez-Vallejo, Fabian Thiemann, Michael Horn-von Hoegen, Klaus Reimann, Michael Woerner, and Thomas Elsaesser
Author(s): Matthias Runge, Ahmed Ghalgaoui, Isabel Gonzalez-Vallejo, Fabian Thiemann, Michael Horn-von Hoegen, Klaus Reimann, Michael Woerner, and Thomas Elsaesser

The semimetal bismuth displays a multifaceted nonlinear terahertz response, which is studied by two-dimensional terahertz (2D-THz) spectroscopy. Nonperturbative excitation drives intra- and interband electron transitions close to the narrow band gaps at the L points of the Brillouin zone, giving rise to pump-probe signals and high-harmonic generation. Preferential excitation in two of the six L valleys generates an anisotropic carrier distribution across the Brillouin zone, causing a hexagonal azimuthal angular dependence of the pump-probe signal. The concomitant symmetry reduction allows excitation of coherent phonon wavepackets along back-folded phonon coordinates.

[Phys. Rev. B 107, 245140] Published Wed Jun 28, 2023

Third-order Hall effect in the surface states of a topological insulator
Tanay Nag, Sanjib Kumar Das, Chuanchang Zeng, and Snehasish Nandy
Author(s): Tanay Nag, Sanjib Kumar Das, Chuanchang Zeng, and Snehasish Nandy

Time reversal and inversion symmetric materials fail to yield linear and nonlinear responses since they possess net zero Berry curvature. However, higher-order Hall response can be generated in these systems upon constraining the crystalline symmetries. Motivated by the recently discovered third-ord…

[Phys. Rev. B 107, 245141] Published Wed Jun 28, 2023

Obstructed atomic insulators and superfluids of fermions coupled to ${\mathbb{Z}}_{2}$ gauge fields
Bhandaru Phani Parasar and Vijay B. Shenoy
Author(s): Bhandaru Phani Parasar and Vijay B. Shenoy

Studying spin-$\frac{1}{2}$ fermions coupled to ${\mathbb{Z}}_{2}$ gauge fields on the square lattice, we show how a spatial modulation of the fermion hopping amplitude allows for the realization of various obstructed atomic insulators that host higher-order band topology. Including the effect of qu…

[Phys. Rev. B 107, 245142] Published Wed Jun 28, 2023

Found 2 papers in prl
Date of feed: Thu, 29 Jun 2023 03:16:59 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]+)

Atom Interferometric Imaging of Differential Potentials Using an Atom Laser
M. E. Mossman, Ryan A. Corbin, Michael McNeil Forbes, and P. Engels
Author(s): M. E. Mossman, Ryan A. Corbin, Michael McNeil Forbes, and P. Engels

Interferometry is a prime technique for modern precision measurements. Atoms, unlike light, have significant interactions with electric, magnetic, and gravitational fields, making their use in interferometric applications particularly versatile. Here, we demonstrate atom interferometry to image opti…

[Phys. Rev. Lett. 130, 263402] Published Wed Jun 28, 2023

Antiferromagnetic Spin Fluctuations and Unconventional Superconductivity in Topological Superconductor Candidate YPtBi Revealed by $^{195}\mathrm{Pt}$-NMR
Y. Z. Zhou, J. Chen, Z. X. Li, J. Luo, J. Yang, Y. F. Guo, W. H. Wang, R. Zhou, and Guo-qing Zheng
Author(s): Y. Z. Zhou, J. Chen, Z. X. Li, J. Luo, J. Yang, Y. F. Guo, W. H. Wang, R. Zhou, and Guo-qing Zheng

Nuclear magnetic resonance spectroscopy offers strong evidence that YPtBi can exhibit topological superconductivity, a property that could be harnessed to build quantum computers.

[Phys. Rev. Lett. 130, 266002] Published Wed Jun 28, 2023

Found 3 papers in nano-lett
Date of feed: Thu, 29 Jun 2023 01:07:21 GMT

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

[ASAP] Side-Chain-Dependent Functional Intercalations in Graphene Oxide Membranes for Selective Water and Ion Transport
Kecheng Guan, Zhaohuan Mai, Siyu Zhou, Shang Fang, Zhan Li, Ping Xu, Yu-Hsuan Chiao, Mengyang Hu, Pengfei Zhang, Guorong Xu, Keizo Nakagawa, and Hideto Matsuyama

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Nano Letters
DOI: 10.1021/acs.nanolett.3c01541

[ASAP] Trion Formation Resolves Observed Peak Shifts in the Optical Spectra of Transition-Metal Dichalcogenides
Thomas Sayer, Yusef R. Farah, Rachelle Austin, Justin Sambur, Amber T. Krummel, and Andrés Montoya-Castillo

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Nano Letters
DOI: 10.1021/acs.nanolett.3c01342

[ASAP] Experimental Demonstration of a Magnetically Induced Warping Transition in a Topological Insulator Mediated by Rare-Earth Surface Dopants
Beatriz Muñiz Cano, Yago Ferreiros, Pierre A. Pantaleón, Ji Dai, Massimo Tallarida, Adriana I. Figueroa, Vera Marinova, Kevin García-Díez, Aitor Mugarza, Sergio O. Valenzuela, Rodolfo Miranda, Julio Camarero, Francisco Guinea, Jose Angel Silva-Guillén, and Miguel A. Valbuena

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Nano Letters
DOI: 10.1021/acs.nanolett.3c00587

Found 2 papers in acs-nano
Date of feed: Wed, 28 Jun 2023 21:20:59 GMT

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

[ASAP] Ultra-Wideband Mid-Infrared Chalcogenide Suspended Nanorib Waveguide Gas Sensors with Exceptionally High External Confinement Factor beyond Free-Space
Mingquan Pi, Chuantao Zheng, Huan Zhao, Zihang Peng, Gangyun Guan, Jialin Ji, Yijun Huang, Yuting Min, Lei Liang, Fang Song, Xue Bai, Yu Zhang, Yiding Wang, and Frank K. Tittel

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ACS Nano
DOI: 10.1021/acsnano.3c02699

[ASAP] Cascaded Logic Gates Based on High-Performance Ambipolar Dual-Gate WSe2 Thin Film Transistors
Xintong Li, Peng Zhou, Xuan Hu, Ethan Rivers, Kenji Watanabe, Takashi Taniguchi, Deji Akinwande, Joseph S. Friedman, and Jean Anne C. Incorvia

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ACS Nano
DOI: 10.1021/acsnano.3c03932