Spin frustration and unconventional spin twisting state in van der Waals ferromagnet/antiferromagnet heterostructures

TL;DR

This study reveals a novel spin twisting state at the interface of vdW ferromagnet/antiferromagnet heterostructures, driven by spin frustration, with implications for understanding magnetic interface phenomena.

Contribution

It uncovers an unconventional spin twisting state caused by spin frustration in vdW heterostructures, a phenomenon not previously observed in such systems.

Findings

Discovery of a perpendicular magnetization at the interface.

Identification of a spin twisting transition from perpendicular to in-plane.

Robust AFM domains unaffected by external magnetic fields.

Abstract

Atomically flat surfaces of van der Waals (vdW) materials pave an avenue for addressing a long-standing fundamental issue of how a perfectly compensated antiferromagnet (AFM) surface frustrates a ferromagnetic (FM) overlayer in FM/AFM heterostructures. By revealing the AFM and FM spin structures separately in vdW Fe5GeTe2/NiPS3 heterostructures, we find that C-type in-plane AFM NiPS3 develops three equivalent AFM domains which are robust against external magnetic field and magnetic coupling with Fe5GeTe2. Consequently, spin frustration at the Fe5GeTe2/NiPS3 interface was shown to develop a perpendicular Fe5GeTe2 magnetization in the interfacial region that switches separately from the bulk of the Fe5GeTe2 magnetizations. In particular, we discover an unconventional spin twisting state that the Fe5GeTe2 spins twist from perpendicular direction near the interface to in-plane direction away from the interface in Fe5GeTe2/NiPS3. Our finding of the twisting spin texture is a unique property of spin frustration in van der Waals magnetic heterostructures.