Current-Induced Instability of a Perpendicular Ferromagnet in Spin Hall   Geometry
  We develop a theoretical formula of spin Hall torque in the presence of two ferromagnets. While the direction of the conventional spin Hall torque always points to the in-plane direction, the present system enables to manipulate the torque direction acting on one magnetization by changing the direction of another magnetization. Based on the diffusion equation of the spin accumulation and the Landauer formula, we derive analytical formula of the spin Hall torque. The present model provides a solution to switch a perpendicular ferromagnet deterministically at zero field using the spin Hall effect. 
Tomohiro Taniguchi, Seiji Mitani, and Masamitsu Hayashi
cond-mat.mes-hall cond-mat.mtrl-sci