Colloquium: A critique on van der Waals and two-dimensional magnets

TL;DR

This paper critically reviews the recent advances in two-dimensional magnetic materials, questioning their novelty and exploring their unique properties and potential for new physics and applications.

Contribution

It provides a nuanced critique of the field, clarifying what is genuinely new about 2D magnets compared to traditional systems and their potential for future research.

Findings

2D magnets are uniquely sensitive to electric fields and mechanical deformation

They offer platforms for revisiting long-standing physics predictions

Their real-world promises are still being realized

Abstract

Magnetic two-dimensional (2D) crystals were isolated about a decade ago, triggering a tremendous research activity worldwide. This colloquium raises a stiff question: what is really new about them? At first sight, they seem to be purer implementations of 2D spin models than traditional systems such as ultra-thin films. Yet, they partly realized their promises so far, and whether they give fresh perspectives on long-standing predictions in statistical physics is still an open question. Undoubtedly, they are uniquely amenable to electric-field effect, susceptible to mechanical deformation, and sensitive to moir\'{e}s, for example. They represent interesting platforms for exploring, challenging, or simply revisiting a wide range of phenomena in condensed matter magnetism. This colloquium intends to offer a critical, yet not necessarily skeptical, overview of the field, clarifying what we believe could be unique with 2D magnets, related quasi-2D van der Waals magnets, and their heterostructures.