Enhanced Spin-Orbit Torques and Magnetization Switching through Interface Engineering

Abstract

The origin of spin-orbit torques generated from the conversion of charge-to-spin currents is of considerable debate. Solid understanding of the physics behind is key to the development of current and voltage controlled switching dynamics in ultrathin heterostuctures. The field free switching observed recently (Phys. Rev. Lett. 120, 117703 (2018)) in a Pt/W/CoFeB structure has intensified such a debate. Here we derive a formula to evaluate a perpendicular effective field generated when the current flows through the heterostructure, considering the large resistivity difference between the two normal metal layers and the chemical potential gradient created at the interface. Together with recent X-ray photoelectron spectroscopy findings at the interface of a Pd/CoFeB structure, we conclude that a new torque generated may play a key role in the field free switching. The model and mechanism proposed agrees with previous reports on spin current injection and field free switching using different interface engineering methods.

18 pages, 4 figures

References in corpus (4)

• Magnetization switching by spin-orbit torque in an antiferromagnet/ferromagnet bilayer system
• Electric field control of deterministic current-induced magnetization switching in a hybrid ferromagnetic/ferroelectric structure
• Interplay of spin-orbit torque and thermoelectric effects in ferromagnet/normal metal bilayers
• Spin-orbit torque engineering via oxygen manipulation