Al doped Ba hexaferrite (BaAl x Fe 12-x O 19 ) thin films on Pt using metallo-organic decomposition

We grew a series of aluminum-substituted M-type barium hexaferrite (BaAl x Fe 12-x O 19 ) thin films on a Pt (111) template and Si wafer using metallo-organic decomposition technique. We varied the composition from x=0 to x=2 with 0.25 step increments. X-ray diffraction patterns confirm highly textured c-axis polycrystalline films while atomic force microscope measurements allow us to estimate the lateral grain sizes which range from 0.2-1 micron depending on Al content. The microwave properties of these films were studied using a broadband ferromagnetic resonance spectrometer from 35 to 70GHz. The measured out of plane effective anisotropy field increases in a nearly linear fashion with increasing Al concentration, between 12.8 kOe for x=0 and 25 kOe for x=2. The measured ferromagnetic resonance linewidths were relatively low, on the order of 150-300Oe for compositions below x=1, increasing significantly up to 800Oe for x=2. The easy axis magnetic hysteresis loops exhibit high squareness.