Development of L1o FePt (001) thin films for perpendicular magnetic recording media

Abstract

Chemically ordered Ll0 (CuAu-I type structure) FePt films with an fct (face centered tetragonal) structure possess a high Ku (magnetic anisotropy constant) value (~ 6-10xl07 erg/cm3), which allows them to have very small thermally stable magnetic grains (~2.6nm) and makes them the most promising candidates for ultra-high areal density recording media. Usually, as-deposited FePt alloy thin films are a disordered fee (facecentered- cubic) phase and tend to show a (111) texture. A high temperature (above 550°C) post annealing is needed to form an ordered Ll0 phase. In order to develop FePt films as perpendicular magnetic recording media, the Ll0 FePt ordering temperature has to be reduced and the easy axis of the films should be perpendicular to the film surface. Moreover, the grain size and exchange coupling between grains should be decreased. Thus, in this thesis, the research has been focused on two main issues (1) how to lower the Llo FePt ordering temperature when getting the crystallographic texture controlled at the same time and, (2) how to decrease the grain size and inter-granular exchange coupling.