Nonvolatile Control of Nonlinear Hall and Circular Photogalvanic Effects via Berry Curvature Dipole in Multiferroic Monolayer CrNBr2

TL;DR

This paper predicts that ferroelectric monolayer CrNBr2 exhibits a large, nonvolatile nonlinear Hall effect and circular photogalvanic response driven by Berry curvature dipoles, with potential applications in nanoelectronics and optoelectronics.

Contribution

It demonstrates that ferroelectricity in monolayer CrNBr2 induces a Berry curvature dipole, enabling nonvolatile control of nonlinear transport effects, a novel finding beyond time-reversal symmetric systems.

Findings

Large nonlinear Hall conductivity observed in CrNBr2.

Circular photogalvanic current is significantly enhanced by ferroelectricity.

Nonvolatile switching of effects via ferroelectric polarization coupling.

Abstract

The Berry curvature dipole induced by symmetry breaking play a pivotal role in electronic transport properties and nonlinear responses, such as the nonlinear Hall effect and circular photogalvanic effect. The study of the Berry curvature dipole, often explored in time-reversal symmetric systems, but it should not be limited to such materials. Here, we predicted that the ferroelectricity in monolayer CrNBr2 produces Berry curvature dipole, leading to the nonlinear Hall effect and circular photogalvanic current. The linear anomalous Hall effect and circularly polarized optical absorption, governed by spin-orbit coupling, are independent of ferroelectric polarization and exhibit extremely small conductance. In contrast, multiferroic monolayer CrNBr2 achieves a large nonlinear Hall conductivity and circular photogalvanic current, despite its suppression at high temperatures from phonon scattering. The coupling between the ferroelectric polarization and the Berry curvature dipoles allows for nonvolatile switching of these effects, presenting substantial promise for nanoelectronic and optoelectronic devices.