Film Thickness Gradient-Induced Magnetic Anisotropy and Ferromagnetic Resonance in Fe 56 Co 24 B 20 Amorphous Films Prepared by Pulse Laser Deposition

The ferromagnetic resonance frequency f FMR of soft magnetic films (SMFs) can be expressed by the Kittel equation. Clearly, high 4pM S and H K are needed to achieve a high f FMR in SMFs. Previous research on achieving high f FMR SMFs has mostly been focused on enhancing uniaxial magnetic anisotropy field H K since it is relatively easier to be enhanced by 1–2 orders of magnitude, compared to saturation magnetization that is capped at 24.5 kGs at room temperature 1 . Magnetron sputtering of SMFs in in-situ magnetic fields and/or subsequent magnetic annealing after deposition have been widely employed for inducing a uniaxial magnetic anisotropy 2 . However, the induced uniaxial magnetic anisotropy fields are usually in the range of 3 . Several different approaches have been investigated for achieving high uniaxial magnetic anisotropy in SMFs, such as composition gradient sputtering 4 , oblique sputtering 5 , facing target sputtering 6 , exchange coupling 7 , and magnetoelectric coupling 8 , etc.