Nonlinear magnetic field dependence of spin polarization in high density two-dimensional electron systems

TL;DR

This study investigates the nonlinear relationship between spin polarization and magnetic field in high-density 2D electron systems, revealing exchange coupling effects as the cause of nonlinearity rather than electron correlation.

Contribution

It demonstrates that the nonlinear P-B dependence arises from P-dependent g* due to exchange coupling, challenging previous assumptions about electron correlation effects.

Findings

P exhibits superlinear increase with magnetic field

Nonlinearity causes differences between Xs and Xgm

Exchange coupling, not electron correlation, causes nonlinearity

Abstract

The spin polarization (P) of high-density InSb two-dimensional electron systems (2DESs) has been measured using both parallel and tilted magnetic fields. P is found to exhibit a superlinear increase with the total field B. This P-B nonlinearity results in a difference in spin susceptibility between its real value Xs and Xgm ~ m*g*(m* and g* are the effective mass and g factor, respectively) as routinely used in experiments. We demonstrate that such a P-B nonlinearity originates from the linearly P-dependent g* due to the exchange coupling of electrons rather than from the electron correlation as predicted for the low-density 2DES.