Dependence of Magnetic Anisotropy in Co_(20)Fe_(60)B_(20) Free Layers on Capping Layers in MgO-Based Magnetic Tunnel Junctions with In-Plane Easy Axis

摘要

Perpendicular magnetic anisotropy (PMA) in Co_(20)Fe_(60)B_(20) films depending on the adjacent layers of Ta, Ru, and MgO was studied for reduction of switching current density J_(20) in in-plane magnetic tunnel junctions (MTJs). A MgO layer reduces the out-of-plane saturation field (H_s) of in-plane easy axis Co_(20)Fe_(60)B_(20) films by inducing a strong PMA at the Co_(20)Fe_(60)B2o/MgO interface. The PMA is not affected much by the crystallinity in Co_(20)Fe_(60)B_(20) films with different capping layers. MTJ with a MgO capping layer shows a lower J∞ than that with a Ru capping layer, in accordance with the reduction of H_s.