Article
Materials Science, Multidisciplinary
Maxim Dzero, Alex Levchenko
Summary: We study a two-dimensional electron system with short-ranged nonmagnetic disorder potential, Coulomb interactions, and Rashba spin-orbit coupling. By employing the path-integral approach within the Keldysh formalism, we derive the kinetic equation for the semiclassical Green's function and use it to calculate the spin current within the linear response theory. The frequency dependence of the spin Hall conductivity is examined, and the role of electron interactions at finite temperatures in both ballistic and diffusive transport regimes is explained.
Article
Physics, Multidisciplinary
Igor Lyalin, Sanaz Alikhah, Marco Berritta, Peter M. Oppeneer, Roland K. Kawakami
Summary: This study reports the direct observation of current-induced orbital accumulation on the surface of a light 3d transition metal, Cr, using magneto-optical detection. The orbital polarization is transverse to the current direction and scales linearly with current density, consistent with the orbital Hall effect.
PHYSICAL REVIEW LETTERS
(2023)
Article
Multidisciplinary Sciences
Xiaokang Li, Yo Machida, Alaska Subedi, Zengwei Zhu, Liang Li, Kamran Behnia
Summary: We observe a thermal Hall conductivity with a large amplitude in a non-magnetic elemental insulator. The presence of this phenomenon in various insulators suggests a common mechanism, although the absolute amplitude varies greatly. The lack of correlation between the thermal Hall angle and the phonon mean-free-path imposes constraints on theoretical explanations.
NATURE COMMUNICATIONS
(2023)
Article
Physics, Multidisciplinary
Pankaj Bhalla, Ming-Xun Deng, Rui-Qiang Wang, Lan Wang, Dimitrie Culcer
Summary: Topological edge states show dissipationless transport. Nonlinear electrical response of ballistic TES confirms the presence of symmetry breaking terms, such as deviations from nonlinearity. The direction of nonlinear response is determined by the spin orientation with respect to the Zeeman field.
PHYSICAL REVIEW LETTERS
(2021)
Article
Multidisciplinary Sciences
T. -W. Zhou, G. Cappellini, D. Tusi, L. Franchi, J. Parravicini, C. Repellin, S. Greschner, M. Inguscio, T. Giamarchi, M. Filippone, J. Catani, L. Fallani
Summary: The Hall effect, which describes the motion of charged particles in magnetic fields, has important implications for material properties. Understanding this effect in interacting systems is challenging, even for small magnetic fields. In this study, we used an atomic quantum simulator to investigate the behavior of ultracold fermions in the presence of artificial magnetic fields. Through experimental measurements, we observed a universal behavior of the Hall response, which is independent of the strength of atomic interactions. This research demonstrates the capability of quantum simulation to describe strongly correlated topological states of matter.
Article
Physics, Multidisciplinary
Yawar Mohammadi, Samira Bahrami
Summary: This paper investigates the effects of Y-shaped Kekule bond texture on the transport coefficients of Kekule-patterned graphene. It is found that this texture lifts the valley degeneracy of all levels except the zero mode, resulting in additional plateaus in the Hall conductivity and a split of the peaks in the longitudinal conductivity. The results also indicate that DC Hall conductivity measurements can determine the amplitude of the Kekule bond texture.
Article
Physics, Fluids & Plasmas
Kang Hao Lee, Vinitha Balachandran, Dario Poletti
Summary: The study demonstrates that giant rectification can still be achieved in segmented chains even when each half chain is interacting, if the two interacting half chains are sufficiently different, possibly due to the emergence of an energy gap. In the thermodynamic limit, perfect rectification does not exist when each half chain is interacting.
Article
Physics, Multidisciplinary
Heda Zhang, Chunqiang Xu, Caitlin Carnahan, Milos Sretenovic, Nishchay Suri, Di Xiao, Xianglin Ke
Summary: The anomalous thermal Hall effect was observed in the insulating van der Waals ferromagnet VI3, with a thermal Hall signal that persists without an external magnetic field. The dual nature of the thermal Hall effect in VI3, dominated by topological magnons and phonons induced by magnon-phonon coupling, positions VI3 as a potential platform for applications in spintronics-magnonics.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Heda Zhang, Chunqiang Xu, Caitlin Carnahan, Milos Sretenovic, Nishchay Suri, Di Xiao, Xianglin Ke
Summary: The study reports the observation of an anomalous thermal Hall effect in the insulating van der Waals ferromagnet VI3, indicating a dual nature of the effect dominated by topological magnons and phonons. These results position VI3 as a potential platform for spintronics-magnonics applications.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Sangwoo Sim, Heejun Yang, Ha-Leem Kim, Matthew J. Coak, Mitsuru Itoh, Yukio Noda, Je-Geun Park
Summary: Measurements of the thermal Hall effect in strontium titanate crystals revealed a significant difference in thermal Hall conductivity between samples with different oxygen isotopes. The relationship between the thermal Hall conductivity and longitudinal thermal conductivity suggests a phonon-mediated thermal Hall effect, but anomalies were observed below the Curie temperature. This observation, along with the correlation with quantum critical fluctuations, suggests a new mechanism linking quantum physics and thermal transport phenomena in nonmagnetic insulating systems.
PHYSICAL REVIEW LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Dominik Lessnich, Stephen M. Winter, Mikel Iraola, Maia G. Vergniory, Roser Valenti
Summary: This paper discusses the applicability of elementary band representations (EBRs) for diagnosing topological phases in interacting insulators. By considering an auxiliary noninteracting system, the use of EBRs on Green's function is demonstrated, but the application of this method in diagnosing symmetry-protected topological phases remains to be discussed.
Article
Multidisciplinary Sciences
Vladislav D. Kurilovich, Zachary M. Raines, Leonid I. Glazman
Summary: In this study, we develop a theory to understand the charge transport along the quantum Hall edge influenced by a superconductor. We find that Andreev reflection of an edge state is typically suppressed unless there is disorder in the superconductor, which makes it random. Consequently, the conductance of a proximitized segment becomes a stochastic quantity with alternating sign fluctuations and zero average. We also determine the statistical distribution of the conductance and how it depends on electron density, magnetic field, and temperature. Our theory provides an explanation for a recent experiment involving a proximitized edge state.
NATURE COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
K. Shizuya
Summary: In equilibrium planer systems of Hall electrons, two species of current counterflowing along the system edges are observed, as recently observed in experiments using a nanoscale magnetometer. The origins and features of these equilibrium currents are examined, considering the Coulombic many-body effects, and their real-space distributions are derived. The analysis is based on a reformulation of quantum Hall systems as a W-infinity gauge theory, allowing for diagonalization of the total Hamiltonian based onexternal probes' resolutions. These equilibrium currents are closely related to the orbital magnetization in quantum Hall systems, with a special focus on the case of graphene and its neutral (nu = 0) ground state and intrinsic diamagnetic response.
Article
Multidisciplinary Sciences
Taiki Uehara, Takumi Ohtsuki, Masafumi Udagawa, Satoru Nakatsuji, Yo Machida
Summary: This study reveals that the thermal conductivity in Pr2Ir2O7 is dominated by phonons, and the resonant scattering of phonons on paramagnetic spins strongly impedes the longitudinal heat current. The resonant scattering is affected by the development of spin ice correlation upon cooling, leading to an anisotropic deviation from the scaling of thermal conductivity with respect to field directions. Additionally, a correlation between longitudinal and transverse thermal conductivity is observed, providing solid evidence for the role of spin-phonon scattering in hindering longitudinal heat conduction and generating transverse response.
NATURE COMMUNICATIONS
(2022)
Article
Physics, Multidisciplinary
Yimin Ji, Wenxu Zhang, Hongbin Zhang, Wanli Zhang
Summary: The spin Hall conductivity (SHC) and anomalous Hall conductivity (AHC) in approximately 120 full Heusler compounds were calculated using density functional theory in a high-throughput manner. The results showed that the mechanism of SHC and AHC cannot be simply explained by valence electron numbers or atomic weights, but rather depends on the details of the electronic structures, which can only be obtained through calculations. High-throughput calculations were efficient in screening desired materials. According to the present results, Rh2MnAl, Cu2CoSn, Co2MnAl, and Co2MnGa are potential candidates for spintronic materials due to their high SHC and AHC values, which could benefit spin-torque-driven nanodevices.
NEW JOURNAL OF PHYSICS
(2022)
Article
Multidisciplinary Sciences
Frank Schindler, Stepan S. Tsirkin, Titus Neupert, B. Andrei Bernevig, Benjamin J. Wieder
Summary: This research shows that corner defects in insulating crystals can bind 0D higher-order end states with anomalous charge and spin. These states are intrinsic consequences of the bulk electronic structure and new bulk topological invariants are introduced to predict these defect states in solid-state materials.
NATURE COMMUNICATIONS
(2022)
Article
Physics, Multidisciplinary
Kevin Zhang, Samuel Lederer, Kenny Choo, Titus Neupert, Giuseppe Carleo, Eun-Ah Kim
Summary: This article introduces the use of neural networks to approximately solve quantum many-body problems, and proposes a new method to evaluate the quality of neural network wavefunctions. Through Hamiltonian reconstruction, the characteristics of reconstructed Hamiltonians in certain situations and the importance of wavefunction symmetry are discovered.
Article
Physics, Multidisciplinary
David M. Urwyler, Patrick M. Lenggenhager, Igor Boettcher, Ronny Thomale, Titus Neupert, Tomas Bzdusek
Summary: In this study, elementary models of hyperbolic topological band insulators were introduced, and their nontrivial topology was revealed by computing topological invariants. The bulk-boundary correspondence was demonstrated, and the robustness of these models against disorder was confirmed.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Bastien Lapierre, Titus Neupert, Luka Trifunovic
Summary: The study shows that fully localized, three-dimensional, time-reversal-symmetry-broken insulators do not belong to a single phase of matter but can realize topologically distinct phases labeled by integers. Phase transition only occurs when the system becomes conducting at some filling, and these novel topological phases are fundamentally different from insulators without disorder in that they guarantee delocalized boundary states with quantized boundary Hall conductance equal to the bulk topological invariant.
PHYSICAL REVIEW LETTERS
(2022)
Article
Multidisciplinary Sciences
Anffany Chen, Hauke Brand, Tobias Helbig, Tobias Hofmann, Stefan Imhof, Alexander Fritzsche, Tobias Kieling, Alexander Stegmaier, Lavi K. Upreti, Titus Neupert, Tomas Bzdusek, Martin Greiter, Ronny Thomale, Igor Boettcher
Summary: In this study, we introduce and experimentally realize hyperbolic matter as a paradigm for topological states using topolectrical circuit networks with a complex-phase circuit element. We confirm hyperbolic band theory through an unprecedented numerical survey of finite hyperbolic lattices. Our work demonstrates the implementation of hyperbolic graphene as an example of topologically nontrivial hyperbolic matter. This research sets the stage for realizing more complex forms of hyperbolic matter and provides a key ingredient for future experimental simulation of various Hamiltonians with topological ground states.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Glenn Wagner, Souvik Das, Johannes Jung, Artem Odobesko, Felix Kuester, Florian Keller, Jedrzej Korczak, Andrzej Szczerbakow, Tomasz Story, Stuart S. P. Parkin, Ronny Thomale, Titus Neupert, Matthias Bode, Paolo Sessi
Summary: Step edges of topological crystalline insulators in Pb1-xSnxSe were studied using scanning tunneling microscopy and spectroscopy. When the energy position of the step edge approaches the Fermi level, a correlation gap opens up. The experimental results suggest that the interaction effects are enhanced due to the collapsing of electronic density into a one-dimensional channel, providing a unique system to study the intertwining of topology and many-body electronic effects. Theoretical modeling was performed through a Hartree-Fock analysis.
Article
Physics, Multidisciplinary
Song-Bo Zhang, Xiaoxiong Liu, Md Shafayat Hossain, Jia-Xin Yin, M. Zahid Hasan, Titus Neupert
Summary: We propose and study a new phase of two-dimensional shifted charge density waves (CDW) that is composed of weakly coupled one-dimensional CDW wires with varying phases. We demonstrate that the fully gapped bulk CDW possesses topological properties, characterized by a non-zero Chern number, which leads to the presence of edge modes within the bulk energy gap. Remarkably, these edge modes exhibit spectral pseudoflow along the edge, analogous to the chiral edge modes of Chern insulators in momentum space. Additionally, we show that the CDW edge modes remain stable even in the presence of interwire coupling. These predictions can be experimentally tested in quasi-one-dimensional CDW compounds such as Ta2Se8I.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Multidisciplinary
Martina O. Soldini, Felix Kuester, Glenn Wagner, Souvik Das, Amal Aldarawsheh, Ronny Thomale, Samir Lounis, Stuart S. P. Parkin, Paolo Sessi, Titus Neupert
Summary: Scientists have extended the idea of the one-dimensional magnetic adatom chain structure to two-dimensional systems, which may host topological states. By placing magnetic adatoms on the surface of a conventional superconductor, lattices of Yu-Shiba-Rusinov bound states can be formed to create topological bands within the superconducting gap.
Article
Materials Science, Multidisciplinary
Omer M. Aksoy, Anirudh Chandrasekaran, Apoorv Tiwari, Titus Neupert, Claudio Chamon, Christopher Mudry
Summary: Fermi surfaces can undergo sharp transitions with topological character when higher-order singularities develop at the transition. Odd singularities appear in pairs within the Brillouin zone when time-reversal and inversion symmetries are present. The combination of enhanced density of states and nesting between the singularities leads to interaction-driven instabilities.
Article
Materials Science, Multidisciplinary
Maciej Bieniek, Jukka I. Vaeyrynen, Gang Li, Titus Neupert, Ronny Thomale
Summary: We theoretically investigate the electronic and transport properties of QSH edge states in large gap 1-T' WTe2 monolayers. We explore the impact of edge termination, disorder, temperature, and interactions on experimentally observable edge state properties. We find that conductance quantization can remain robust even for heavily disordered samples, and that moderate disorder can enhance the stability of conductance by localizing bulk states. We also evaluate the edge state velocity and Luttinger liquid parameter as functions of the chemical potential, finding prospects for physics beyond linear helical Luttinger liquids.
Article
Physics, Multidisciplinary
Dominik Kiese, Francesco Ferrari, Nikita Astrakhantsev, Nils Niggemann, Pratyay Ghosh, Tobias Mueller, Ronny Thomale, Titus Neupert, Johannes Reuther, Michel J. P. Gingras, Simon Trebst, Yasir Iqbal
Summary: This study investigates the quantum phase diagram of the spin S = 1/2 Heisenberg antiferromagnet on the kagome lattice. It reveals that the ground state of the nearest-neighbor antiferromagnet transitions from U(1) Dirac spin liquid to a pinwheel valence bond crystal with half moons in its structure factor at intermediate coupling strengths, and to a collinear magnetically ordered state characterized by starlike patterns at larger couplings. This finding is important for further understanding and developing highly tunable Heisenberg antiferromagnets.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Materials Science, Multidisciplinary
Song -Bo Zhang, M. Michael Denner, Tomas Bzdusek, Michael A. Sentef, Titus Neupert
Summary: The Hatano-Nelson model, a one-dimensional non-Hermitian chain of spinless fermions, was studied in the presence of repulsive nearest-neighbor interactions. Two PT transitions were found, with the first one being a first-order symmetry-breaking transition into a charge-density wave regime. Persistent currents characteristic of the model disappear abruptly at this transition. The second transition, which only occurs in finite-size systems, is characterized by the collapse of all energy eigenvalues onto the real axis. In addition, in a strong interaction regime, the many-body spectrum exhibits point gaps with nontrivial winding numbers, similar to the topological properties of the single-particle spectrum of the Hatano-Nelson chain, indicating the skin effect of extensive many-body eigenstates under open boundary conditions.
Article
Materials Science, Multidisciplinary
Armando Consiglio, Tilman Schwemmer, Xianxin Wu, Werner Hanke, Titus Neupert, Ronny Thomale, Giorgio Sangiovanni, Domenico Di Sante
Summary: In this study, the structural and electronic properties of kagome metals AV(3)Sb(5) (A = Cs, K, Rb) under isotropic and anisotropic pressure were investigated using first-principles calculations. The results show that the charge-ordering patterns are suppressed and there is a significant rearrangement of Van Hove point energies. The findings suggest a mechanism for tuning the correlation profile in kagome metals and provide insights for further experimental investigations on unconventional pairing and multidome superconductivity.
Article
Materials Science, Multidisciplinary
Arkadiy Davydov, Kenny Choo, Mark H. Fischer, Titus Neupert
Summary: This work presents a computationally efficient workflow for obtaining the low-energy symmetric tight-binding Hamiltonians for twisted multilayer systems. The workflow is applied to twisted bilayer graphene at the first magic angle. The full-energy tight-binding Hamiltonian is generated using the SlaterKoster model, and then the low-energy symmetric four-band and 12-band Hamiltonians are constructed using the maximum-localization procedure. Extended Hubbard parameters are computed within the constrained random phase approximation for screening. The workflow demonstrated on twisted bilayer graphene can be easily applied to other twisted multilayer materials.
Article
Physics, Multidisciplinary
Ao Chen, Kenny Choo, Nikita Astrakhantsev, Titus Neupert
Summary: In this study, a neural network method suitable for systems with real-valued wave functions is proposed, encoding the sign structure of a quantum wave function in a convolutional neural network with discrete output. The training is achieved through an evolutionary algorithm. The results demonstrate that this method can accurately converge to the known sign structures of ordered phases and obtain better variational energies compared to other neural network states in cases where the sign structures are a priori unknown.
PHYSICAL REVIEW RESEARCH
(2022)
