Reduction of Coercivity of Fe-N Soft Magnetic Film by Heat Treatment

200 nm thick Fe-N magnetic thin films were deposited on glass substrates by RF sputtering. The as-deposited films havehigh saturation magnetization but their coercivity is also higher than what is needed Therefore it is very important to reducecoercivity. The samples were vacuum annealed at 250℃ under 12000 A/m magnetic field. When the N content was in therange of 5～7 at. pct, the thin films consisted of α′ + α″ after heat treatment and had excellent soft magnetic properties of4rMs=2.4 T, HC ＜80 A/m. However, the thickness of a recording head was 2μm, andHc increased as thickness increased.In order to reduce the Hc, the sputtering power was raised from 200 W to 1000 W to reduce the grain size. 2μm Fe-N thinfilms were vacuum annealed under the same condition, when the N content was in the range of 5.9～8.5 at. pct, the thin filmskept its excellent magnetic properties of 4πMs=2.2 T, HC ＜80 A/m. The properties of the films meet the need of a recordinghead material used in the dual-element GMR/inductive heads.