Electrical magnetochiral anisotropy and quantum metric in chiral conductors

TL;DR

This paper uncovers the quantum geometric origins of electrical magnetochiral anisotropy in chiral conductors, highlighting the significant role of Dirac states and quantum metric, and explores the emergence of topological insulator states with spin-orbit coupling.

Contribution

It introduces a quantum geometry perspective to EMCA in chiral conductors and demonstrates the impact of Dirac states and quantum metric on nonlinear magnetoresistance.

Findings

Dirac states significantly contribute to EMCA near the Dirac point.

Quantum metric influences both longitudinal and transverse EMCA.

Spin-orbit coupling can induce a topological insulator state.

Abstract

Electrical magnetochiral anisotropy (EMCA) refers to the chirality- and current-dependent nonlinear magnetoresistance in chiral conductors and is commonly interpreted in a semiclassical picture. In this work, we reveal a quantum geometry origin of EMCA using a chiral rectangular lattice model that resembles a chiral organic conductor (DM-EDT-TTF)${}_2$ClO${}_4$ studied for EMCA recently and exhibits symmetry-protected Dirac bands similar to those of graphene. Compared to the semiclassical term, we find that Dirac states contribute significantly to both traditional longitudinal EMCA and the unconventional transverse EMCA via the quantum metric when Fermi energy is close to the Dirac point. Besides, we discover that a topological insulator state can emerge once spin-orbit coupling (SOC) is added to our chiral model lattice. Our work paves a path toward understanding quantum geometry in the magnetotransport of chiral materials.