Anomalous Hall Coulomb drag of massive Dirac fermions

TL;DR

This paper investigates how the anomalous Hall effect influences Coulomb drag in massive Dirac fermion systems, revealing a transverse drag current that is independent of active-layer magnetization and varies with passive-layer magnetization.

Contribution

It demonstrates that the topological Berry curvature does not contribute to Coulomb drag, but an anomalous Hall drag current arises in the passive layer, independent of the active-layer magnetization.

Findings

The topological term from Berry curvature does not affect Coulomb drag.

A transverse drag current exists in the passive layer, independent of active-layer magnetization.

The drag current varies non-monotonically with passive-layer magnetization, peaking at low densities.

Abstract

Dirac fermions are actively investigated, and the discovery of the quantized anomalous Hall effect of massive Dirac fermions has spurred the promise of low-energy electronics. Some materials hosting Dirac fermions are natural platforms for interlayer coherence effects such as Coulomb drag and exciton condensation. Here we determine the role played by the anomalous Hall effect in Coulomb drag in massive Dirac fermion systems. We focus on topological insulator films with out-of plane magnetizations in both the active and passive layers. The transverse response of the active layer is dominated by a topological term arising from the Berry curvature. We show that the topological mechanism does not contribute to Coulomb drag, yet the longitudinal drag force in the passive layer gives rise to a transverse drag current. This anomalous Hall drag current is independent of the active-layer magnetization, a fact that can be verified experimentally. It depends non-monotonically on the passive-layer magnetization, exhibiting a peak that becomes more pronounced at low densities. These findings should stimulate new experiments and quantitative studies of anomalous Hall drag.