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

TL;DR

This paper demonstrates that applying an electric field can induce a nonlinear anomalous Nernst effect in time-reversal symmetric 2D materials by breaking mirror symmetry, with potential for experimental detection using second-harmonic techniques.

Contribution

It reveals how electric fields enable NANE in symmetric 2D systems and proposes a method for experimental observation through alternating temperature gradients.

Findings

Electric field lifts mirror symmetry, enabling NANE in 2D materials.

NANE arises from Berry connection polarization and Berry curvature corrections.

Theoretical analysis of NANE behavior in monolayer graphene.

Abstract

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.