Co-Ferrite Thin Films With Perpendicular Magnetic Anisotropy

Co-ferrite thin film with spinel structure is attractive for spintronics and multifunctional devices. So far, single-crystal substrates are necessary to introduce perpendicular magnetic anisotropy in co-ferrite films. In this paper, a unique process has been developed to deposit co-ferrite thin films onto thermally oxidized silicon wafer with perpendicular magnetic anisotropy. We have successfully prepared co-ferrite films with (00l) orientation. Those films show perpendicular coercivities as large as 12.8 kOe. X-ray diffractometry results revealed that compressive strain, which is introduced by the postannealing process rather than deposition process, is as large as 1.3% in films with (00l) orientation. The large coercivity and perpendicular magnetic anisotropy can be quantitatively explained by the magnetoelastic effect. This silicon-compatible fabrication process is useful to further extending the applications of co-ferrite films.