Annealing effect on the longitudinal and transverse incremental permeability in FeSmO thin films

The transverse permeability ratio (TPR) and longitudinal permeability ratio (LPR) as a function of an external field of FeSmO films have been investigated in conjunction with thermal treatment. The FeSmO films were prepared by the RF magnetron sputtering method in Ar atmosphere. The film annealed at 500°C has the maximum value of the incremental permeability ratio (PR) due to the ultrasoft magnetic materials. The LPR curve shows the single-peak pattern, and the TPR curve shows the double-peak pattern indicating the existence of the magnetic anisotropy effect. The magnetic anisotropy and the magnitude of the incremental permeability are strongly dependent on the magnetic softness due to the annealing. The large changes of LPR and TPR in low external fields can be useful for the evaluation of the magnetic softness as well as the magnetic sensor applications.