Unidirectional magnetoresistance in the van der Waals antiferromagnet CrPS4

As a typical nonlinear magnetoresistance, unidirectional magnetoresistance (UMR) has recently been observed in antiferromagnetic (AFM) systems with canted spin structure. However, a profound understanding of AFM UMR induced by interfacial spin-orbit coupling (SOC) is still lacking to date. In this paper, we choose van der Waals canted antiferromagnetic CrPS4 due to the relatively low magnetic anisotropy and weak interlayer coupling, which enables a canted-AFM state between two adjacent layers under an in-plane magnetic field, and systematically investigate SOC-induced AFM UMR in CrPS4/Pt heterostructure. We experimentally observe two characteristic UMR tendencies versus magnetic field in CrPS4/Pt devices. The different UMR tendencies may be attributed to the interfacial defect-induced Fermi level change, which is supported by density-functional theory calculations and Boltzmann transport formalism. Our work provides a more profound understanding of the nontrivial AFM UMR and may facilitate the development of two-dimensional AFM spintronic devices.