In-plane current induced spin orbit effects in nanometer scale Hall bar of $\beta $-W/Ta/CoFeB/MgO/Ta multilayers

The giant spin Hall effect (GSHE) is caused by spin orbit interactions in a semiconductor or metal that result in a spin current that is transverse to the charge current. Recent spin Hall effect studies in the beta phase metals Ta and W show that transverse spin currents are strong enough to switch an adjacent magnetic layer. Films with perpendicular magnetic anisotropy (PMA) can exhibit uniform magnetizations and higher thermal stability. Inserting a 1 nm Ta insert-layer between the CoFeB and W induces PMA which is confirmed by vibrating sample magnetometer and anomalous Hall voltage measurements. $\beta $-W(5)/Ta(1) channel and the adjacent CoFeB/MgO/Ta layers are patterned into a 100 nm wide Hall bar structures. Effect of in-plane current induced change in coercivity while sweeping in-plane magnetic field are studied. An empirical model to quantitatively understand the switching will be presented.