Thermal stability and the origin of perpendicular anisotropy in amorphous Tb-Fe-Co films

Both the thermal stability of the material parameters and the effect of annealing on magnetic anisotropy have been investigated for amorphous Tb27Fe53Co20 films. On the basis of the coexistence of the pseudodipolar interaction and the stress coupled with magnetostriction, a numerical computation is performed on fitting the change of the perpendicular anisotropy Ku with temperature and Ku variations affected by annealing at the various temperatures, respectively. We show that the anisotropy originates from both the internal stress and the pseudodipolar interaction with the anisotropic part of the Ruderman-Kittel-Kasuya-Yosida exchange interaction, in which a contribution from Tb-Fe atom pairs is dominant. The change of the material parameters occurs after relatively short annealing. We attribute it to the thermal relaxation of internal stress at lower temperatures