Effect of a change in thickness on the structural and perpendicular magnetic properties of L1 ordered FePd ultra-thin films with (001) texture

Abstract

Ultra-thin FePd films were prepared by the sputter-deposition of Fe and Pd layers. After annealing at 500 °C, they transformed to a (001) oriented L10 ordered phase from an A1 disordered phase and changed their anisotropy to perpendicular magnetic anisotropy from in-plane. The ordered parameter was about 0.7 for all thicknesses of the FePd films. The 20 nm-thick FePd film exhibited the squareness of 0.3 because both the disordered phase with in-plane magnetic anisotropy and ordered phase with perpendicular magnetic anisotropy existed in the FePd film. The disordered phase was reduced, and the L10 phase became predominated as the thickness of the FePd films decreased. In particular, when the FePd films were 3 and 5 nm thick, the squareness became unity while maintaining a thermal stability factor of over 60. The uniaxial magnetic anisotropy constant Ku was over 1 × 107 erg/cm3. Those characters make ultra-thin L10 FePd films suitable for use in nano-devices for magnetic applications.