Enhancement of perpendicular magnetic anisotropy through reduction of Co-Pt interdiffusion in (Co/Pt) multilayers

We demonstrate that the effective magnetic anisotropy of sputtered (Co/Pt) multilayers can be doubled by limiting the interdiffusion occurring at Co/Pt interfaces. We present a way to decrease the interdiffusion by inserting an ultra-thin Cu layer at or near the Co/Pt interfaces. When such a material is sputtered on Co prior to the Pt deposition, the perpendicular magnetic anisotropy, as well as the thermal stability, is enhanced for Co layer thicknesses smaller than 1 nm. This is of great interest for out-of-plane magnetized spintronic devices which require high perpendicular magnetic anisotropy for down-size scalability reasons together with a free layer as thin as possible to reduce the writing energy when switched by spin transfer torque.