arXiv subjects

Ying-Li Wu

Publications and source records attributed to Ying-Li Wu.

6 recordsLinked to original sources

arXiv2026

Electric-field controlled nonlinear anomalous Nernst effect in two-dimensional time-reversal symmetric systems

It's established that the nonlinear anomalous Nernst effect (NANE), originating from Berry curvature near the Fermi energy, is symmetry-permitted only when a single mirror symmetry exists in the transport plane of two-dimensional (2D) materials. Here, we show that an applied direct electric field can lift this symmetry constraint, enabling an electric-field-induced NANE emerge in time-reversal symmetric 2D systems with higher crystallographic symmetries. This electric-field-induced NANE arises from both Berry connection polarization, rooted in the electric-field-corrected Berry curvature, and the anomalous-velocity-modified nonequilibrium Fermi distribution function. Additionally, we propose an alternating temperature gradient as a driving force instead of the conventional steady one, ensuring experimental detection of NANE via second-harmonic measurement techniques. The behaviour of electric-field-induced NANE in the monolayer graphene has been theoretically and systematically investigated.

cond-mat.mes-hall↗

arXiv2025

Intrinsic nonlinear valley Nernst effect in the strained bilayer graphene

We theoretically analyze the nonlinear valley Nernst effect (NVNE) as the second-order response of temperature gradient through the semiclassical framework of electron dynamics. Our study shows that an intrinsic nonlinear pure valley current can be generated vertically to the applied temperature in the materials with both inversion and time-reversal symmetries. This intrinsic NVNE has a quantum origin from the quantum metric and shows independence from the relaxation time. We find that the local largest symmetry near the valleys for the nonvanishing intrinsic NVNE is a single mirror symmetry in two-dimensional systems. We theoretically investigate the intrinsic NVNE in the uniaxially strained gapless bilayer graphene and find the intrinsic NVNE can emerge when applying the temperature gradient vertically to the direction of strain. Interestingly, a transition from the compressive strain to the tensile one results in the sign reversal of the intrinsic NVNE.

cond-mat.mes-hall↗

arXiv2025

The unidirectional Seebeck detection of the Néel vector in the two-dimensional tetragonal $\mathcal{PT}$-symmetric antiferromagnetic materials

The efficient detection of the reversal (180$^{\circ}$ rotation) of the Néel vector is one of the crucial tasks in antiferromagnetic spintronics. Here, we propose a thermal approach to detect the reversal of the Néel vector in the tetragonal $\mathcal{PT}$ antiferromagnetic materials through the unidirectional Seebeck effect (USE). Being different from the previous works in which USE stems from the global Rashba spin-orbit coupling (SOC) or asymmetric magnon scattering, we find that the USE originates from the coupling of the hidden Rashba SOC and the Néel vector in the tetragonal $\mathcal{PT}$ antiferromagnetic materials in the absence of the global Rashba SOC. Using a generic minimal model, we analyse the behaviors of the USE for the two-dimensional tetragonal lattice $\mathcal{PT}$ antiferromagnet. Importantly, It's found that when the Néel vector is reversed, the sign of the USE changes, which can be utilized to detect the reversal of the Néel vector.

cond-mat.mes-hall↗

arXiv2025

Extrinsic nonlinear acoustic valley Hall effect in the massive Dirac materials

The nonlinear acoustic valley Hall effect (AVHE), a recently discovered novel acoustically driven phenomena, has sparked extensive interests in valleytronics. So far, only the intrinsic contributions from band structure (Berry curvature or asymmetric energy dispersions) to nonlinear AVHE have been investigated. Here, we theoretically investigate the nonlinear AVHE from both intrinsic and extrinsic contributions in two-dimensional (2D) hexagonal massive Dirac materials with disorders based on the Boltzmann formalism and also concretely analyse the behaviours of nonlinear AVHE in disordered monolayer MoS2. It's found that the extrinsic contributions (side jump and skew scattering) can also give rise to a pure nonlinear AVHE in the 2D hexagonal massive Dirac materials. Remarkably, the extrinsic mechanisms dominate the nonlinear AVHE in the disordered monolayer MoS2.

cond-mat.mes-hall↗

arXiv2024

Strongly enhanced nonlinear acoustic valley Hall effect in tilted Dirac materials

It has been recently established that a nonlinear valley current could be generated through traveling a surface acoustic wave (SAW) in two-dimensional Dirac materials. So far, the SAW-driven valley currents have been attributed to warping Fermi surface or Berry phase effect. Here, we demonstrate that tilt mechanism can also lead to a nonlinear valley Hall current (VHC) when propagating SAW in materials with the tilted Dirac cone placed on a piezoelectric substrate. It's found that the nonlinear VHC exhibits a $\sinθ$ dependence on the orientation of tilt with respect to SAW. In addition, this tilt-induced nonlinear acoustic VHC shows independence on the relaxation time, distinguishing from the contributions from the Berry phase or trigonal warping. Remarkably, the magnitude of the nonlinear acoustic VHC from tilt mechanism in the uniaxially strained graphene is two orders larger than those reported in MoS$_2$ stemmed from the Berry phase effect and the warping effect.

cond-mat.mes-hall↗

arXiv2023

Unidirectional Seebeck effect from Rashba spin-orbit coupling on the subsurface of Ge(111)

A new nonlinear magnetothermal effect, namely unidirectional Seebeck effect(USE), has been recently reported in magnetic/nonmagnetic topological insulator (TI) heterostructure and is ascribed to the asymmetry magnon scattering. Here, we show a new mechanism to generate USE in the Rashba two dimensional electron gas (2DEG), in which the magnetism or magnetic order is completely absent. It's found that the USE has a quantum origin from the spin-momentum locking generated from Rashba spin-orbit coupling. We find that the USE exhibits a sine dependence on the orientation of the magnetic field with respect to the direction of the temperature gradient and is dominant from the states above the Lifshitz point. The USE in the semiconductor Ge(111) subsurface states has been theoretically and systematically investigated.

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