Spontaneous Spin Polarization in Quantum Wires

TL;DR

This paper explains how strong electron interactions in quantum wires can cause spontaneous spin polarization, despite theoretical restrictions, by inducing deviations from ideal one-dimensional geometry.

Contribution

It demonstrates that electron interactions can lead to ferromagnetic ground states in quantum wires, challenging the Lieb-Mattis theorem.

Findings

Strong interactions induce deviations from 1D geometry.

Spontaneous spin polarization occurs at certain electron densities.

Ferromagnetic ground states are possible in quantum wires.

Abstract

A number of recent experiments report spin polarization in quantum wires in the absence of magnetic fields. These observations are in apparent contradiction with the Lieb-Mattis theorem, which forbids spontaneous spin polarization in one dimension. We show that sufficiently strong interactions between electrons induce deviations from the strictly one-dimensional geometry and indeed give rise to a ferromagnetic ground state in a certain range of electron densities.