The thermodynamic spin magnetization of strongly correlated 2d electrons in a silicon inversion layer

TL;DR

This study introduces a new method to measure the thermodynamic spin magnetization of dilute 2D electrons in silicon, revealing enhanced susceptibility due to ferromagnetic interactions and localization effects, without spontaneous magnetization.

Contribution

A novel measurement technique for thermodynamic spin magnetization in 2D electrons, showing the interplay of ferromagnetic interactions and disorder near localization transition.

Findings

Susceptibility increased up to 7.5 times the Pauli value

Magnetization peaks near localization transition density

Susceptibility approaches that of free spins (Curie law)

Abstract

A novel method invented to measure the minute thermodynamic spin magnetization of dilute two dimensional fermions is applied to electrons in a silicon inversion layer. Interplay between the ferromagnetic interaction and disorder enhances the low temperature susceptibility up to 7.5 folds compared with the Pauli susceptibility of non-interacting electrons. The magnetization peaks in the vicinity of the density where transition to strong localization takes place. At the same density, the susceptibility becomes extremely close to that of free spins (Curie susceptibility), indicating an almost perfect compensation of the kinetic energy toll associated with spin polarization by the energy gained from the ferromagnetic correlation. Yet, the balance favors a paramagnetic phase over spontaneous magnetization.