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

摘要

We report a giant spin Hall effect in β-W thin films. Using spin torque induced ferromagnetic resonance with a β-W/CoFeB bilayer microstrip, we determine the spin Hall angle to be |θ_(SH)~(β-w)| = 0.30±0.02, 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 β-W layer. From switching data obtained with such 3-terminal devices, we independently determine |θ_(SH)~(β-w)| = 0.33±0.06. We also report variation of the spin Hall switching efficiency with W layers of different resistivities and hence of variable (a and _(SH)~(β-w)) phase composition.