Spin-independent origin of the strongly enhanced effective mass in a dilute 2D electron system

TL;DR

This study measures the effective mass in a dilute 2D electron system in silicon, revealing a sharp increase with decreasing density that is independent of spin polarization, challenging existing theories.

Contribution

It provides the first precise measurement showing spin-independent effective mass enhancement in dilute 2D electron systems, contradicting prior theoretical predictions.

Findings

Effective mass sharply increases as electron density decreases.

Mass enhancement is independent of spin polarization.

Results challenge existing spin-dependent interaction theories.

Abstract

We have accurately measured the effective mass in a dilute two-dimensional electron system in silicon by analyzing temperature dependence of the Shubnikov-de Haas oscillations in the low-temperature limit. A sharp increase of the effective mass with decreasing electron density has been observed. Using tilted magnetic fields, we have found that the enhanced effective mass is independent of the degree of spin polarization, which points to a spin-independent origin of the mass enhancement and is in contradiction with existing theories.