Spin-flip-driven anisotropic magnetoresistance in antiferromagnetic spin-valve-like structure

A spin valve is a prototype of spin-based electronic devices found on ferromagnets, in which an antiferromagnet plays a supporting role. Recent findings in antiferromagnetic spintronics show that an antiferromagnetic order in single-phase materials solely governs dynamic transport, and antiferromagnets are considered promising candidates for spintronic technology. In this study, antiferromagnet-based spintronic functionality on single crystals of Ca_0.9Sr_0.1Co₂As₂ was demonstrated by integrating nanoscale spin-valve-type structure and anisotropic magnetic properties driven by spin-flips. Multiple stacks of 1 nm thick spin-valve-like unit are intrinsically embedded in the antiferromagnetic spin structure. The switching operation between low and high resistance states was observed in the presence of a rotating magnetic field. This leads to anisotropic magnetoresistance, which is maximized in the vicinity of the flip transition. Phenomenological calculations based on an easy-axis anisotropic spin model reproduce observed magnetic and magnetotransport properties and suggest an essential role of magnetocrystalline anisotropy in the observed spintronic functionality. Our results observed in a natural antiferromagnet offer the potential of utilizing spin flip/flop transitions in extensive spintronic applications.