Use of film thickness and Cu additive to improve (0Â 0Â 1) texture in MgO/FePtCu(C) bilayers

A multilayer structure has been proposed that demonstrates improved (0 0 1) texture for FePt-based L10 perpendicular media. Achieving a strong perpendicular magnetic anisotropy requires aligning the L10 crystallographic c-axis along the film normal. The ordered L10 FePt structure is tetragonal with a c/a ratio close to 0.965. This makes discriminating between the three crystallographic variants ([1 0 0], [0 1 0], and the desired [0 0 1]) difficult. Alloying FePt with Cu to reduce the c/a ratio and using a multilayer approach to keep the magnetic layers thin results in a structure with an adjustable Mrt and a strong (0 0 1) texture (rocking curve widths around 2°). This is a remarkable improvement in texture from pure FePt multilayered films or monolithic FePt(X) films. The proposed [MgO(2 nm)/Fe50−xPt50Cux(5 nm)]×n structure limits grain size in the vertical (perpendicular) direction albeit not in the plane of the film. Carbon can be added to the FePtCu layer to reduce the grain size with minimal degradation of the (0 0 1) orientation.