Angular momentum transfer torques in spin valves with perpendicular magnetization

TL;DR

This paper investigates the angular dependence of spin-transfer torque in perpendicular magnetization spin valves using first-principles calculations and compares with experiments, predicting a non-monotonous torque with Ru spacers.

Contribution

It provides first-principles calculations of spin-transfer torque in perpendicular spin valves and predicts a novel non-monotonous torque behavior with Ru spacers.

Findings

Agreement between calculations and experiments on CoFe|Cu|CoNi systems.

Prediction of a non-monotonous 'wavy' torque with Ru spacers.

Identification of angular dependence in spin-transfer torque.

Abstract

Spin valves incorporating perpendicularly magnetized materials are promising structures for memory elements and high-frequency generators. We report the angular dependence of the spin-transfer torque in spin valves with perpendicular equilibrium magnetization computed by first-principles circuit theory and compare results with experiments by W.H. Rippard c.s. [Phys. Rev. B 81, 014426 (2010)] on the CoFe|Cu|CoNi system. Furthermore, we predict a non-monotonous ("wavy") spin-transfer torque when the Cu spacer is replaced by a Ru layer.