Ferromagnetic interlayer exchange coupling in a few layers of CrSBr on a gold thin film

TL;DR

This study demonstrates that thin CrSBr layers on gold exhibit ferromagnetic order due to substrate-induced electron transfer, with implications for tuning 2D magnet properties in spintronics.

Contribution

It reveals ferromagnetic ordering in few-layer CrSBr on gold, driven by substrate electron transfer, supported by experimental imaging and theoretical calculations.

Findings

CrSBr on Au shows ferromagnetic ground state for layers <11 nm.

Electron transfer from Au stabilizes ferromagnetism in CrSBr.

Electronic band structure of CrSBr is modified when on Au.

Abstract

The two-dimensional character of van der Waals magnets allows for efficient control of their properties via proximity effects and electrical stimuli, making them promising candidates for application in spin-electronics. We use spin-polarized low energy electron microscopy to directly image the magnetic texture of thin CrSBr on top of a Au film, uncovering a ferromagnetic ground state for CrSBr thicknesses smaller than 11 nm. We argue that the stabilization of the ferromagnetic ordering - as compared to the conventional antiferromagnetic one - is obtained via electron transfer from the Au film to the CrSBr flakes, in agreement with ab-initio density functional theory calculations. Reflected-electron spectroscopy shows clear differences in the unoccupied density of states between a few layers of CrSBr on Au and bulk CrSBr, pointing towards electronic band structure modification in thin CrSBr. This work sheds light on the possibility to tune magnetic properties of two-dimensional magnets via substrate engineering.