Deposition temperature induced magnetic anisotropy variation in FePt-C soft/hard multilayer films

Multilayer exchange spring media were fabricated by subsequently reducing the deposition temperature of the FePt-C film from the bottom layer to the top layer. Magnetic anisotropy and coercivity of FePt-C film increased with the increasing of deposition temperature because the chemical ordering of L10 FePt improved with deposition temperature. A two-layer microstructure was observed in the multilayer samples with a closely-packed granular hard layer and an isolated granular overlayer consisting of the soft magnetic layers deposited at lower temperatures. The coercivity of the tri-layer media was reduced to 5.4 kOe, half of that of the hard single layer FePt-C (10.8 kOe). The thermal stability of the multilayer structure was maintained although some soft magnetic layers involved.