Multiple order spin-wave resonance in composition gradient sputtering FeCoB thin films

FeCoB films with different B doping contents and different thicknesses were deposited by composition gradient sputtering. The results show that in-plane anisotropy fields and exchange constants change with the increasing B contents and increasing thickness, respectively. Both results of the composition-gradient films and the thickness-dependent films and the micromagnetic simulation indicate that multiple order spin-wave resonances are easy to obtain in the films with the large in-plane anisotropy field. We observed four resonance peaks including three perpendicular standing spin waves. The hysteresis loop and magnetic domain results indicate that such films also have good magnetic softness and an in-plane homogeneous domain structure.