Enhancement of Perpendicular Magnetic Anisotropy and Transmission of Spin-Hall-Effect-Induced Spin Currents by a Hf Spacer Layer in W/Hf/CoFeB/MgO Layer

摘要

We report that strong perpendicular magnetic anisotropy of the ferromagneticlayer in a W/CoFeB/MgO multilayer structure can be established by inserting aHf layer as thin as 0.25 nm between the W and CoFeB layers. The Hf spacer alsoallows transmission of spin currents generated by an in-plane charge current inthe W layer to apply strong spin torque on the CoFeB, thereby enablingcurrent-driven magnetic switching. The antidamping-like and field-likecomponents of the spin torque exerted on a 1 nm CoFeB layer are of comparablemagnitudes in this geometry. Both components originate from the spin Halleffect in the underlying W layer.