Linear magnetoresistance in metals: guiding center diffusion in a smooth random potential

TL;DR

This paper predicts a semi-classical mechanism where guiding center diffusion causes a linear, non-saturating magnetoresistance in 3D metals, explaining recent experimental observations in Dirac materials.

Contribution

It introduces a new semi-classical theory linking guiding center diffusion to linear magnetoresistance in metals with smooth disorder potentials.

Findings

Guiding center diffusion leads to linear, non-saturating magnetoresistance.

The theory applies when transport time exceeds cyclotron period and disorder is weak and smooth.

Linear magnetoresistance persists at room temperature for strong disorder potentials.

Abstract

We predict that guiding center (GC) diffusion yields a linear and non-saturating (transverse) magnetoresistance in 3D metals. Our theory is semi-classical and applies in the regime where the transport time is much greater than the cyclotron period, and for weak disorder potentials which are slowly varying on a length scale much greater than the cyclotron radius. Under these conditions, orbits with small momenta along magnetic field $B$ are squeezed and dominate the transverse conductivity. When disorder potentials are stronger than the Debye frequency, linear magnetoresistance is predicted to survive up to room temperature and beyond. We argue that magnetoresistance from GC diffusion explains the recently observed giant linear magnetoresistance in 3D Dirac materials.