Enhanced magnetic properties in FePt (001) epitaxial thin films by Cu capping layer

FePt thin films with Cu capping layer have been fabricated in order to study the microstructure and magnetic properties at 300°C. The enhancement of the coercivity is due to the reduced exchange coupling of FePt magnetic grains originated from Cu atoms diffusion along grain boundaries. Studies of angular dependent coercivity show a tendency of a domain-wall motion shift toward rotation of reverse-domain type with Cu capping layer onto the FePt films. The intergrain interaction was confirmed from the Kelly-Henkel plot that indicated the strong exchange coupling between neighboring grains in the FePt films without Cu addition. On the other hand, negative ¿M value was obtained while the FePt films capped with Cu layer, indicating the Cu capping layer can lead to the reduction of intergrain exchange coupling thus presence of dipole interaction in the Cu/FePt epitaxial thin films.