Crystal Structure and Magnetic Properties of Mn-Al-Ni Ferromagnetic Films

Mn60-xAl40Nix ternary films were prepared by dc magnetron sputtering and their crystallographic characteristics and magnetic properties were investigated. The ¿ phase was synthesized at Ni contents below 7 at%. The lattice constant a increased from 3.98 Å to 4.12 Å, and c decreased from 3.48 Å to 3.21 Å, as a result of increasing the Ni substitution. The Ms of the ¿-phase films increased with increasing Ni substitution up to an Ni content of a few percent. The maximum values for Ms and Hc, 240 emu/cc and 2.9 kOe respectively, were obtained at an Ni content of 3 at%. The high Hc was due to the increased asymmetry of the tetragonal structure. The magnetic anisotropy of ¿-phase films was caused mainly by the preferential orientation of the c-axis of the tetragonal crystallites.