Hall Drag and Magnetodrag in Graphene

TL;DR

This paper explains the giant magnetodrag observed in graphene near charge neutrality by showing how magnetic fields couple energy and charge modes, predicting strong Hall drag and energy-driven magnetodrag at weak fields.

Contribution

It introduces a theoretical framework for magnetodrag in graphene that accounts for coupled energy and charge modes under magnetic fields, predicting phenomena not seen in weak coupling regimes.

Findings

Giant magnetodrag explained by coupled energy and charge modes.

Prediction of strong Hall drag near charge neutrality.

Magnetodrag and Hall drag depend strongly on field and density.

Abstract

Massless Dirac fermions in graphene at charge neutrality form a strongly interacting system in which both charged and neutral (energy) modes play an important role. These modes are essentially decoupled in the absence of a magnetic field, but become strongly coupled when a field is applied. We show that these ideas explain the recently observed giant magnetodrag, arising in classically weak fields when electron density is tuned near charge neutrality. We predict strong Hall drag in this regime, which is in stark departure from the weak coupling regime, where theory predicts the absence of Hall drag. Energy-driven magnetodrag and Hall drag arise in a wide temperature range and at weak magnetic fields, and feature an unusually strong dependence on field and carrier density.