Interaction of Ta-O and perpendicular magnetic anisotropy of Ta/Pd (0-2.4Â nm)/Co2FeAl0.5Si0.5/MgO/Ta structured films

Perpendicular magnetic anisotropy (PMA) was realized by inserting Pd layer into the stack of Ta/Pd (0-2.4 nm)/Co2FeAl0.5Si0.5/MgO/Ta. The realization of PMA is accompanied by the (Co, Fe)-O reduction at Co2FeAl0.5Si0.5/MgO interface under annealing. Without inserting Pd layer, the annealed Ta/Co2FeAl0.5Si0.5/MgO/Ta film presents an in-plane magnetization. Through X-ray photoelectron spectrometry analyzes, it was found that the oxygen was enriched at the interface of Ta/Co2FeAl0.5Si0.5. This work clarifies that the inserted Pd layer effectively blocks the diffusion of interfacial oxygen to Ta layer, achieving the beneficial redox reaction at Co2FeAl0.5Si0.5/MgO interface to realize PMA.