SURFACE AND BULK ANISOTROPY OF RE-TM FILMS FOR MAGNETO-OPTIC RECORDING

Magnetic perpendicular anisotropy of RF-sputtered amorphous TbFe/SiN thin films have been investigated. Anisotropy constants were evaluated from both magnetization curves and magneto-optic effects dependences on in-plane magnetic field. Significant difference was observed between the magnetic anisotropy of the whole film and that measured from its surface, and the difference depended on preparation conditions and film thickness. It was proposed that the incoherent magnetization rotation in external field was induced by very thin highly-magnetized surface layer, which was exchange coupled with the film. Therefore the observed value of the anisotropy energy differs from the intrinsic anisotropy value of unoxidized volume.