ASNISOTROPY AND FARADAY-EFFECT IN CO SPINELO FERRITE FILMS

Crystalline Co spinel ferrite films were prepared by rf sputtering on glass substrates without buffer layer and annealed at temperatures fro m 400 to 600-degrees-C for 2 h in air. (100) texture was obtained in t hese films. The anisotropy constant, magnetic hysteresis loops, and ma gneto-optical Faraday spectra of the films were measured. The texture became poor when the films were annealed below 500-degrees-C, but the perpendicular anisotropy constant K(u), squareness ratio R = (Mr/Ms)pe rpendicular-to/(Mr/Ms)parallel-to increased and showed peak values of 2.2X10(5) ergs/cm3 and 0.94, respectively, at an annealing temperature T(a) = 500-degrees-C. For the film annealed at 600-degrees-C (higher than the Curie temperature, 520-degrees-C, of Co spinel ferrite), the texture recovered, but K(u) and R dropped. The Faraday rotation spectr a of Co spinel ferrite films showed a broad peak centered around 720 n m. The peak value increased monotonically with increasing annealing te mperature. These results may be related to the Co ion-induced anisotro py and Co ion distribution in tetrahedral sites and octahedral sites.