Angular momentum transfer torques in spin valves with perpendicular magnetization

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 Rippard on the CoFe|Cu|CoNi system. Furthermore, we predict a nonmonotonous (wavy) spin-transfer torque when the Cu spacer is replaced by a Ru layer.