Valley splitting of AlAs two-dimensional electrons in a perpendicular magnetic field

TL;DR

This study investigates how magnetic fields influence valley splitting in high-mobility AlAs 2D electrons, revealing a magnetic field-dependent splitting likely caused by electron-electron interactions.

Contribution

It provides the first detailed measurement of valley splitting in AlAs 2D electrons using the coincidence method under tilted magnetic fields.

Findings

Valleys are nearly degenerate without magnetic field.

Valley splitting increases with perpendicular magnetic field.

Electron-electron interactions likely cause the splitting.

Abstract

By measuring the angles at which the Landau levels overlap in tilted magnetic fields (the coincidence method), we determine the splitting of the conduction-band valleys in high-mobility two-dimensional (2D) electrons confined to AlAs quantum wells. The data reveal that, while the valleys are nearly degenerate in the absence of magnetic field, they split as a function of perpendicular magnetic field. The splitting appears to depend primarily on the magnitude of the perpendicular component of the magnetic field, suggesting electron-electron interaction as its origin.