Discovery of an insulating ferromagnetic phase of electrons in two dimensions

TL;DR

This paper comments on recent experimental discoveries of electron nematicity and insulating ferromagnetism in a 2D electron system, discussing their implications and theoretical phase diagrams.

Contribution

It summarizes key experimental findings and offers theoretical insights into the phase diagram of strongly correlated 2D electrons.

Findings

Observation of electron nematicity

Detection of insulating ferromagnetism

Discussion of phase diagram features

Abstract

This is a commentary on two papers (PNAS 117 (51) 32244-32250 (2020) and arXiv:2011.06721), which observed a series of ordering transitions in a strongly correlated two-dimensional electron system confined to a AlAs quantum well. We summarize the main discoveries (electron nematicity, insulating ferromagnetism, etc.) of them and speculate on $T-r_s$ phase diagram based on theoretical considerations.