Colossal magnetoresistance in an ultra-clean weakly interacting 2D Fermi liquid

TL;DR

This paper reports a colossal magnetoresistance effect in a high-mobility 2D electron system in GaAs, likely caused by magneto-orbital coupling and a field-induced 2D-to-3D transition, without a metal-insulator transition.

Contribution

It presents the first observation of colossal magnetoresistance in an ultra-clean 2D Fermi liquid, attributed to magneto-orbital effects rather than spin or localization.

Findings

Magnetoresistance increases by a factor of ~300 up to 45T

No metal-insulator transition occurs during the magnetoresistance increase

The effect is consistent with a 2D-to-3D electronic transition

Abstract

We report the observation of a new phenomenon of colossal magnetoresistance in a 40 nm wide GaAs quantum well in the presence of an external magnetic field applied parallel to the high-mobility 2D electron layer. In a strong magnetic field, the magnetoresistance is observed to increase by a factor of ~300 from 0 to 45T without the system undergoing any metal-insulator transition. We discuss how this colossal magnetoresistance effect cannot be attributed to the spin degree-of-freedom or localization physics, but most likely emanates from strong magneto-orbital coupling between the two-dimensional electron gas and the magnetic field. Our observation is consistent with a field-induced 2D-to-3D transition in the confined electronic system.