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

TL;DR

This paper presents a novel field-free switching method for perpendicular magnetic tunnel junctions using a bent current channel to generate inhomogeneous spin-orbit torques, enabling deterministic switching without external magnetic fields.

Contribution

Introduces a scalable, material-agnostic, field-free switching scheme for SOT-MTJs by shaping the current path to produce inhomogeneous spin-orbit torques.

Findings

Demonstrated deterministic switching in scaled SOT-MTJs.

Achieved switching at nanosecond time scales.

Compatible with wafer-scale manufacturing.

Abstract

Current-induced spin-orbit torques (SOTs) enable fast and efficient manipulation of the magnetic state of magnetic tunnel junctions (MTJs), making it attractive for memory, in-memory computing, and logic applications. However, the requirement of the external magnetic field to achieve deterministic switching in perpendicular 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 non-uniform 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.