Interplay among spin, orbital effects and localization in a GaAs two-dimensional electron gas in a strong in-plane magnetic field

TL;DR

This study investigates how spin, orbital effects, and localization influence magnetoresistance in a disordered GaAs 2D electron gas under high in-plane magnetic fields, revealing localization's significant role in spin polarization.

Contribution

It demonstrates the impact of localization on spin polarization and compares experimental results with theoretical predictions in disordered systems.

Findings

Complete spin polarization occurs at lower fields than in disorder-free models.

Localization significantly affects the effective size of the Fermi sea.

Electron-electron interactions are enhanced at low densities.

Abstract

The magnetoresistance of a low carrier density, disordered GaAs based two-dimensional (2D) electron gas has been measured in parallel magnetic fields up to 32 T. The feature in the resistance associated with the complete spin polarization of the carriers shifts down by more than 20 T as the electron density is reduced, consistent with recent theories taking into account the enhancement of the electron-electron interactions at low densities. Nevertheless, the magnetic field for complete polarization, Bp, remains 2-3 times smaller than predicted for a disorder free system. We show, in particular by studying the temperature dependance of Bp to probe the effective size of the Fermi sea, that localization plays an important role in determining the spin polarization of a 2D electron gas.