Giant field-tunable nonlinear Hall effect by Lorentz skew scattering in a graphene moire superlattice

TL;DR

This paper reports a giant, field-tunable nonlinear Hall effect in a graphene-hBN moire superlattice caused by Lorentz skew scattering, offering a new efficient way to control NHE beyond traditional quantum effects.

Contribution

It introduces a classical-quantum cooperative mechanism for a giant, tunable NHE driven by magnetic fields in a moire superlattice, surpassing previous quantum-based methods.

Findings

Nonlinear Hall effect reaches 32% of linear signal.

Nonlinear Hall conductivity up to 36000 μmV-1Ω-1.

NHE exhibits a quartic scaling law near van Hove singularities.

Abstract

The nonlinear Hall effect (NHE) can enable rectification and energy harvesting, and its control by external fields, including gate, strain and magnetic field, has been pursued intensively. However, existing tuning pathways rely predominantly on fully quantum mechanical effects and are typically inefficient, resulting in weak NHE signals that limit further progress. In this work, we report the discovery of a distinct type of NHE in a graphene-hBN moire superlattice, which arises from a classical-quantum cooperative effect called Lorentz skew scattering (LSK), induced by a perpendicular magnetic field. This field-driven NHE exhibits a linear dependence on magnetic field and a pronounced unidirectional angular dependence. Remarkably, its magnitude reaches up to 32% of the linear Hall signal. We show that this giant, field-tunable NHE originating from LSK follows a unique quartic scaling law and produces a record-high nonlinear Hall conductivity (36000 {\mu}mV-1{\Omega}-1) near van Hove singularities of moire minibands, which is over an order of magnitude larger than all previously reported NHEs. Our findings establish an efficient, magnetic-field-driven route to giant Hall rectification in high-mobility materials, offering a broadly applicable paradigm for modulating the NHE beyond electrostatic gating.