Efficient Control of Stochastic Switching via Spin Pumping in Antiferromagnetic Structures

Abstract

Electrically controlled switching in an antiferromagnet (AFM), utilizing a currentless mechanism, is theoretically examined at finite temperatures. The structure consists of a metallic AFM with biaxial magnetic anisotropy sandwiched between a ferromagnetic spin filter and a semiconductor Schottky junction in a two-terminal pillar configuration. The calculations show that the torque necessary for the desired ${90}^{\ensuremath{\circ}}$ rotation of the N\'eel vector between two easy axes can be provided efficiently by pumping spin-polarized electrons into and out of the AFM through the metallic ferromagnetic layer. Consideration of thermal fluctuations illustrates the stochastic nature of the switching, whose probability distribution can be tailored by the electrical signal pulse as well as by the device dimensions. Detection of the N\'eel-vector state following this rotation may also be achieved straightforwardly via the large anisotropic magnetoresistance of the biaxial antiferromagnetic material. These properties, along with an ultrafast switching speed and a low energy requirement, are expected to be well suited for applications in nonvolatile memory and probabilistic computing.