Tunable zero-field ferromagnetic resonance frequency from S to X band in oblique deposited CoFeB thin films

Tunable zero-field ferromagnetic resonance frequency in wide range is very useful for the application of microwave devices. We performed an investigation of the static and high frequency magnetic properties for oblique sputtered CoFeB thin films. The static magnetic results revealed that oblique sputtered CoFeB thin films possess well defined in-plane uniaxial magnetic anisotropy, which increases monotonically from 50.1 to 608.8 Oe with the increasing of deposition angle from 10 degrees to 70 degrees. Continuous modification of the resonance frequency of CoFeB thin films in a range of 2.83-9.71 GHz (covers three microwave bands including S, C and X bands) has been achieved. This behavior can be explained as the result of the microstructure due to the self-shadowing effect mainly. These CoFeB thin films with tunable magnetic properties may be good candidates for usage in microwave devices.