Pressure-controlled interlayer magnetism in atomically thin CrI3

TL;DR

This study demonstrates that applying hydrostatic pressure can irreversibly switch the interlayer magnetic coupling in atomically thin CrI3 from antiferromagnetic to ferromagnetic, linked to a stacking order change, opening new avenues for magnetic control.

Contribution

It reveals pressure-induced interlayer magnetic phase transition in atomically thin CrI3 linked to stacking order change, a novel control mechanism for 2D magnetism.

Findings

Irreversible AF to FM transition observed under pressure

Stacking order change from monoclinic to rhombohedral confirmed

Interlayer FM coupling in thin CrI3 achieved, matching bulk properties

Abstract

Stacking order can significantly influence the physical properties of two-dimensional (2D) van der Waals materials. The recent isolation of atomically thin magnetic materials opens the door for control and design of magnetism via stacking order. Here we apply hydrostatic pressure up to 2 GPa to modify the stacking order in a prototype van der Waals magnetic insulator CrI3. We observe an irreversible interlayer antiferromagnetic (AF) to ferromagnetic (FM) transition in atomically thin CrI3 by magnetic circular dichroism and electron tunneling measurements. The effect is accompanied by a monoclinic to a rhombohedral stacking order change characterized by polarized Raman spectroscopy. Before the structural change, the interlayer AF coupling energy can be tuned up by nearly 100% by pressure. Our experiment reveals interlayer FM coupling, which is the established ground state in bulk CrI3, but never observed in native exfoliated thin films. The observed correlation between the magnetic ground state and the stacking order is in good agreement with first principles calculations and suggests a route towards nanoscale magnetic textures by moir\'e engineering.