Annealing behavior of amorphous ferromagnetic Cohyphen;Fehyphen;B and Fehyphen;B thin films

摘要

The annealing behavior of amorphous Cohyphen;Fehyphen;B and Fehyphen;B thin films, fabricated by rf sputtering in an argon plasma, have been investigated. The magnetostrictive Fehyphen;B films exhibit a perpendicular anisotropy in the ashyphen;deposited condition, but after a stress relief anneal an inhyphen;plane anisotropy is obtained. An inhyphen;plane easy axis develops in the ashyphen;deposited Cohyphen;Fehyphen;B thin films. The inhyphen;plane anisotropy direction in both sets of films can be rotated by annealing in an external magnetic field aligned parallel to the hard axis via a thermally activated process. Preannealing with a magnetic field aligned parallel to the easy axis stabilizes these films to a significant extent. The kinetics of easy axis rotation has a simple logarithmic dependence on time. Analysis of the kinetics of easy axis rotation indicates that preannealing apparently increases the thermal activation energy for this rotation process.