1208.1711 (Chi-Feng Pai et al.)

Spin transfer torque devices utilizing the giant spin Hall effect of
tungsten    [PDF]

Chi-Feng Pai, Luqiao Liu, Y. Li, H. W. Tseng, D. C. Ralph, R. A. Buhrman

We report a giant spin Hall effect (SHE) in {\beta}-W thin films. Using spin torque induced ferromagnetic resonance with a {\beta}-W/CoFeB bilayer microstrip we determine the spin Hall angle to be |\theta|=0.30\pm0.02, large enough for an in-plane current to efficiently reverse the orientation of an in-plane magnetized CoFeB free layer of a nanoscale magnetic tunnel junction adjacent to a thin {\beta}-W layer. From switching data obtained with such 3-terminal devices we independently determine |\theta|=0.33\pm0.06. We also report variation of the spin Hall switching efficiency with W layers of different resistivities and hence of variable ({\alpha} and {\beta}) phase composition.

View original: http://arxiv.org/abs/1208.1711