Microwave properties of pulsed laser deposited Sc-doped barium hexaferrite films

The properties of thick ${\mathrm{BaSc}}_x{\mathrm{Fe}}_{\text{12−x}}{\mathrm{O}}_{\mathrm{19}}$ $\text{(0.3<x<0.6)}$ scandium hexaferrite films were measured by static and microwave field techniques. Films were deposited by pulsed laser ablation onto c-plane sapphire at oxygen pressures of 20 and 50 mTorr. Vibrating sample magnetometer measurements as corroborated by x-ray data showed that the films below 3 μm had easy axis of magnetization (c-axis) normal to the film plane with saturation magnetization values of 3.0–3.8 kG. From the ferrimagnetic resonance frequency versus external magnetic field, we deduced a g value of $\text{1.96±0.03}$ and uniaxial anisotropy field of ∼10 kOe. The ferrimagnetic resonance linewidth for the film thicker than 5 μm was maximum at 32 GHz and decreased with increasing frequency, indicating evidence for nonuniform magnetic field scattering internally. However, the linewidths were lower for films having thickness below 3 μm.