Field-Free Spin-Orbit Torque Driven Switching of Perpendicular Magnetic Tunnel Junction through Bending Current.

Kateel, Vaishnavi; Krizakova, Viola; Rao, Siddharth; Cai, Kaiming; Gupta, Mohit; Monteiro, Maxwel Gama; Yasin, Farrukh; Sorée, Bart et al. · Nano Lett · 2023

basic_science · Level V

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Abstract

Current-induced spin-orbit torques (SOTs) enable fast and efficient manipulation of the magnetic state of magnetic tunnel junctions (MTJs), making them attractive for memory, in-memory computing, and logic applications. However, the requirement of the external magnetic field to achieve deterministic switching in perpendicularly magnetized SOT-MTJs limits its implementation for practical applications. Here, we introduce a field-free switching (FFS) solution for the SOT-MTJ device by shaping the SOT channel to create a "bend" in the SOT current. The resulting bend in the charge current creates a spatially nonuniform spin current, which translates into inhomogeneous SOT on an adjacent magnetic free layer enabling deterministic switching. We demonstrate FFS experimentally on scaled SOT-MTJs at nanosecond time scales. This proposed scheme is scalable, material-agnostic, and readily compatible with wafer-scale manufacturing, thus creating a pathway for developing purely current-driven SOT systems.