Spin Susceptibility of Interacting Two-dimensional Electrons with Anisotropic Effective Mass

TL;DR

This study measures the spin susceptibility of dilute anisotropic 2D electrons in AlAs, revealing significant interaction effects and highlighting the need for improved theoretical models for anisotropic systems.

Contribution

It provides experimental data on spin susceptibility in anisotropic 2D electrons and discusses the limitations of current isotropic theoretical models.

Findings

Spin susceptibility increases as electron density decreases.

Enhancement of spin susceptibility is less than predicted by isotropic models.

Anisotropic effective mass significantly influences interaction effects.

Abstract

We report measurements of the spin susceptibility in dilute (rs up to 10) AlAs two-dimensional (2D) electrons occupying a single conduction-band valley with an anisotropic in-plane Fermi contour, characterized by longitudinal and transverse effective masses, ml and mt. As the density is decreased, the spin susceptibility is significantly enhanced over its band value, reflecting the role of interaction. Yet the enhancement is suppressed compared to the results of quantum Monte Carlo based calculations that take the finite thickness of the electron layer into account but assume an isotropic effective mass equal to sqrt(ml.mt). Proper treatment of an interacting 2D system with an anisotropic effective mass therefore remains a theoretical challenge.