Structure and Magnetic Properties of Hydrothermal-Treated Cu-Zn Ferrite/CuO Multilayers

The Cu0.8Zn0.4Fe2O4 ferrite/CuO multilayers (CZF ML) were obtained by RF sputtering. These ML were given hydrothermal heat treatment for phase stabilization. The X-ray diffraction pattern show the CZF spinel ferrite phase in all the multilayered films. The CuO-monoclinic phase appeared as the number of CuO layers (n) increased. The field emission electron micrographs show clear nonmagnetic (NM) CuO separations with columnar growth structure for the multilayers. The micrographs in surface view show uniform cluster distribution. The magnetization (M(H)) plots at 80 and 300 K show anisotropy as a function of angle between applied field (H) and ML surface. The oscillatory magnetization behavior is observed for H perpendicular to ML surface. It is more pronounced when H is perpendicular to ML surface than when it is parallel to it. At low temperature, the increased saturation magnetization is observed due to ferromagnetic cluster formation. The structural-induced magnetic anisotropy is verified using FMR spectra of the ML films with a number of NM separations.