A series of (FePt)100-xCux (x = 0, 5, 8 and 11) thin films have been prepared by RF sputtering.
The as-deposited films are nanocrystalline with fine particles. Upon annealing, the films transfer to the
ordered fct FePt phase, which is hard magnetic. The influences of the Cu content, as well as the heat
treatment conditions, on the magnetic properties of the films have been studied. Addition of 5 - 8 at.% Cu
lowers the optimum annealing temperature and improves the magnetic squareness and convexity of the
hysteresis loop. Addition of a higher Cu content weakens the hard magnetic properties of the films. The
dependence of the hard phase formation on the annealing conditions is investigated.
