Nuclear spin ferromagnetic phase transition in an interacting 2D electron gas

TL;DR

This paper demonstrates that in a 2D electron gas, hyperfine interactions can induce a nuclear spin ferromagnetic phase transition at finite temperatures, with electron interactions significantly raising the transition temperature.

Contribution

It introduces a Kondo lattice model to describe nuclear-electron interactions and predicts a finite-temperature ferromagnetic transition in 2D electron gases.

Findings

Nuclear spins undergo a ferromagnetic phase transition at finite temperatures.

Electron-electron interactions enhance the nuclear spin Curie temperature.

Non-Fermi liquid behavior influences the phase transition.

Abstract

Electrons in a two-dimensional semiconducting heterostructure interact with nuclear spins via the hyperfine interaction. Using a a Kondo lattice formulation of the electron-nuclear spin interaction, we show that the nuclear spin system within an interacting two-dimensional electron gas undergoes a ferromagnetic phase transition at finite temperatures. We find that electron-electron interactions and non-Fermi liquid behavior substantially enhance the nuclear spin Curie temperature into the $mK$ range with decreasing electron density.