Multiple-stable anisotropic magnetoresistance memory in antiferromagnetic MnTe

TLDR

Commercial magnetic memories rely on the bistability of ordered spins in ferromagnetic materials. The authors demonstrate a multiple‑stable memory device in epitaxial MnTe, an antiferromagnetic counterpart of common II–VI semiconductors. Using MnTe’s favorable micromagnetic properties, the authors show that its zero‑field antiferromagnetic anisotropic magnetoresistance varies smoothly with the writing field angle, enabling electrical read‑out of multiple memory states set by heat‑assisted recording and field direction, with stability arising from domain distributions along three easy axes. The device demonstrates robust, multiple‑stable memory states that withstand strong magnetic field perturbations, highlighting a unique advantage of antiferromagnets over ferromagnetic counterparts.

Abstract

Abstract Commercial magnetic memories rely on the bistability of ordered spins in ferromagnetic materials. Recently, experimental bistable memories have been realized using fully compensated antiferromagnetic metals. Here we demonstrate a multiple-stable memory device in epitaxial MnTe, an antiferromagnetic counterpart of common II–VI semiconductors. Favourable micromagnetic characteristics of MnTe allow us to demonstrate a smoothly varying zero-field antiferromagnetic anisotropic magnetoresistance (AMR) with a harmonic angular dependence on the writing magnetic field angle, analogous to ferromagnets. The continuously varying AMR provides means for the electrical read-out of multiple-stable antiferromagnetic memory states, which we set by heat-assisted magneto-recording and by changing the writing field direction. The multiple stability in our memory is ascribed to different distributions of domains with the Néel vector aligned along one of the three magnetic easy axes. The robustness against strong magnetic field perturbations combined with the multiple stability of the magnetic memory states are unique properties of antiferromagnets.