Cobaltous oxide infiltrated yttrium iron garnet thin films as high-coercivity media for data storage

Abstract

Significant enhancement in the saturation magnetization Ms and coercivity Hc of yttrium iron garnet (YIG) films has been obtained by a simple method of surface infiltration of CoO. Deposition of a CoO overlayer under specific conditions by a low-pressure chemical-vapor deposition process over the crystallized YIG film has been observed to show high out-of-plane Hc and Ms values of 282.7 and 85.7 kA/m, respectively. The effect of the CoO deposition rate, temperature dependence of coercivity Hc, and annealing studies have been described that indicate CoO infiltration during the growth, resulting in a Co-rich YIG layer, and generation of interfacial stress are responsible for this unusual effect. Delineation of the interface by ion-beam etching in conjunction with magnetic studies has led to the understanding of the nature of the Co-rich YIG interfacial layer. Enhanced Hc and Ms values without the usual method of Ce4+ compensation of Co-doped YIG films described in this letter are of considerable use for application in high-density magneto-optic recording media.