Thermodynamic magnetization of a strongly correlated two-dimensional electron system

TL;DR

This study measures thermodynamic magnetization in a strongly correlated 2D electron system in silicon, revealing a critical growth in spin susceptibility driven mainly by effective mass enhancement, indicating a possible phase transition.

Contribution

It introduces a parameter-free method to directly measure spectrum characteristics and shows that mass enhancement, not g-factor, drives the critical spin susceptibility growth.

Findings

Spin susceptibility grows critically at low electron densities.

Effective mass enhancement dominates over g-factor in susceptibility growth.

Evidence suggests a phase transition in the 2D electron system.

Abstract

We measure thermodynamic magnetization of a low-disordered, strongly correlated two-dimensional electron system in silicon. Pauli spin susceptibility is observed to grow critically at low electron densities - behavior that is characteristic of the existence of a phase transition. A new, parameter-free method is used to directly determine the spectrum characteristics (Lande g-factor and the cyclotron mass) when the Fermi level lies outside the spectral gaps and the inter-level interactions between quasiparticles are avoided. It turns out that, unlike in the Stoner scenario, the critical growth of the spin susceptibility originates from the dramatic enhancement of the effective mass, while the enhancement of the g-factor is weak and practically independent of the electron density.