Magnetic anisotropy and high-frequency property of flexible FeCoTa films obliquely deposited on a wrinkled topography.

We investigated the magnetic anisotropy and the high-frequency property of flexible Fe60 Co26 Ta14 (FeCoTa) thin films obtained by oblique sputtering onto a wrinkled surface. The sinuously wrinkled topography is produced by growing Ta layer on a pre-strained polydimethylsiloxane (PDMS) membrane. Due to the enhanced effect of shadowing, the oblique deposition of FeCoTa layer gives rise to a shift of wrinkle peak towards the incident atomic flux. With increasing the PDMS pre-strain or increasing the oblique sputtering angle, both the uniaxial magnetic anisotropy and the ferromagnetic resonance frequency of FeCoTa films are enhanced, but the initial permeability decreases. The magnetization reversal mechanism of wrinkled FeCoTa films can be interpreted by a two-phase model composed of both coherent rotation and domain wall nucleation. With the enhancement of uniaxial magnetic anisotropy, the domain wall nucleation becomes pronounced in FeCoTa films.