Film Thickness Gradient-Induced Magnetic Anisotropy and Ferromagnetic Resonance in Fe56Co24B20 Amorphous Films Prepared by Pulse Laser Deposition

Fe
₅₆
Co
₂₄
B
₂₀
amorphous films with a large thickness gradient were prepared by pulse laser deposition via moving the sample shutter. The film thickness is varied from 274 to 28.7 nm for a sample with 25 mm in length. The thickness gradient gives rise to a well-defined uniaxial magnetic anisotropy (UMA) with the hard-axis along the direction of thickness gradient. A gradually increased UMA field H
_K
was induced from 110 to 245 Oe along the thickness gradient direction by the interface stress. As a result, the ferromagnetic resonance frequencies f
_FMR
increase from 3.79 to 5.76 GHz with the film thinning.