Lowering critical current density for spin-orbit torque induced magnetization switching by ion irradiation

摘要

In ferromagnet/heavy metal heterostructures, critical current density (J(C)) refers to the minimum current density required to generate spin-orbit torque (SOT) for effective magnetization manipulation, including switching of magnetization and moving of domain walls and magnetic skyrmions. This critical current density is a key factor for next-generation SOT-based magnetic random access memory, racetrack memory, and logic devices. In this work, the critical current density for magnetization switching and the thermal stability of Pt/Co/Ta heterostructures in response to ion irradiation are studied. It is found that ion irradiation represents a promising approach for the wide tuning of the magnetic properties, such as the coercive force and the perpendicular magnetic anisotropy constant. It is also found that J(C) is significantly reduced after 500eV Ar+ irradiation. Meanwhile, the ratio between the thermal stability factor E/k(B)T and J(C) increases with an increase in the irradiation dose, although E/k(B)T decreases slightly with the irradiation dose. This work demonstrates that J(C) can be significantly reduced by an appropriate ion irradiation process and thereby demonstrates a promising approach for effective reduction of the power consumption in SOT-based spintronic devices.