Current-induced CrI3 surface spin-flop transition probed by proximity magnetoresistance in Pt

TL;DR

This study uses proximity magnetoresistance measurements in Pt/CrI3 heterostructures to reveal a current-induced surface spin-flop transition in CrI3, demonstrating a new method to control antiferromagnetic spin states for spintronics.

Contribution

It introduces a novel approach to probe and control surface spin states in CrI3 using proximity MR, highlighting current-induced spin-flop transitions in a van der Waals antiferromagnet.

Findings

Abrupt MR jumps at 2 T indicating spin-flop transition

MR jump magnitude increases with current density

Strong interlayer antiferromagnetic coupling in surface layers

Abstract

By exploiting proximity coupling, we probe the spin state of the surface layers of CrI3, a van der Waals magnetic semiconductor, by measuring the induced magnetoresistance (MR) of Pt in Pt/CrI3 nano-devices. We fabricate the devices with clean and stable interfaces by placing freshly exfoliated CrI3 flake atop pre-patterned thin Pt strip and encapsulating the Pt/CrI3 heterostructure with hexagonal boron nitride (hBN) in a protected environment. In devices consisting of a wide range of CrI3 thicknesses (30 to 150 nm), we observe that an abrupt upward jump in Pt MR emerge at a 2 T magnetic field applied perpendicularly to the layers when the current density exceeds 2.5x10^10 A/m2, followed by a gradual decrease over a range of 5 T. These distinct MR features suggest a spin-flop transition which reveals strong antiferromagnetic interlayer coupling in the surface layers of CrI3. We study the current dependence by holding the Pt/CrI3 sample at approximately the same temperature to exclude the joule heating effect, and find that the MR jump increases with the current density, indicating a spin current origin. This spin current effect provides a new route to control spin configurations in insulating antiferromagnets, which is potentially useful for spintronic applications.