Anomalous spin-splitting of two-dimensional electrons in an AlAs Quantum Well

TL;DR

This study measures the effective g-factor of 2D electrons in an AlAs quantum well, revealing a significantly enhanced and nearly constant value across various magnetic fields, indicating anomalous spin-splitting behavior.

Contribution

It provides the first detailed measurement of the effective g-factor in high-mobility AlAs quantum wells and uncovers its unexpected constancy and enhancement.

Findings

Effective g-factor is approximately 9.0, much larger than bulk value.

The g-factor remains nearly constant over a wide range of magnetic fields.

Spin-splitting behavior shows anomalies not explained by bulk properties.

Abstract

We measure the effective Lande g-factor of high-mobility two-dimensional electrons in a modulation-doped AlAs quantum well by tilting the sample in a magnetic field and monitoring the evolution of the magnetoresistance oscillations. The data reveal that |g| = 9.0, which is much enhanced with respect to the reported bulk value of 1.9. Surprisingly, in a large range of magnetic field and Landau level fillings, the value of the enhanced g-factor appears to be constant.