Strong perpendicular magnetic anisotropy in Co₂FeAl_0.5Si_0.5 film sandwiched by MgO layers

Co₂FeAl_0.5Si_0.5 (CFAS) based multilayers sandwiched by MgO layers have been deposited and annealed at different temperatures. Perpendicular magnetic anisotropy (PMA) with the magnetic anisotropy energy density K_u ≈ 2.5×10⁶ erg/cm³ and the coercivity H_c=363 Oe has been achieved in the Si/SiO₂/MgO (1.5 nm)/CFAS (2.5 nm)/MgO (0.8 nm)/Pt (5 nm) film annealed at 300 ℃. The strong PMA is mainly due to the top MgO layer. The structure can be used as top magnetic electrodes in half-metallic perpendicular magnetic tunnel junctions.