Nonmonotonous classical magneto-conductivity of a two-dimensional electron gas in a disordered array of obstacles

TL;DR

This study combines magnetotransport experiments and molecular dynamics simulations to reveal a nonmonotonous magnetoconductivity peak in a disordered 2D electron gas, linked to directed electron motion around obstacles.

Contribution

It demonstrates the first experimental and simulation evidence of a magnetoconductivity peak caused by directed electron motion in a disordered Lorentz gas, challenging existing kinetic theories.

Findings

Magnetoconductivity exhibits a pronounced peak as a function of magnetic field.

Peak correlates with the onset of directed electron motion along obstacle contours.

Directed motion causes transient superdiffusive behavior near insulator-conductor transitions.

Abstract

Magnetotransport measurements in combination with molecular dynamics (MD) simulations on two-dimensional disordered Lorentz gases in the classical regime are reported. In quantitative agreement between experiment and simulation, the magnetoconductivity displays a pronounced peak as a function of perpendicular magnetic field $B$ which cannot be explained in the framework of existing kinetic theories. We show that this peak is linked to the onset of a directed motion of the electrons along the contour of the disordered obstacle matrix when the cyclotron radius becomes smaller than the size of the obstacles. This directed motion leads to transient superdiffusive motion and strong scaling corrections in the vicinity of the insulator-to-conductor transitions of the Lorentz gas.