The effect of Ce doping on the structure, surface morphology and magnetic properties of Dy doped-yttrium iron garnet films prepared by a sol-gel method

摘要

Cerium substitute Y_(2.8-x)Dy_(0.2)Ce_xFe_5O_(12) (x=0, 0.2, 0.25, 0.3, 0.35) films have been prepared on quartz substrates by a simple sol-gel method and followed by a spin-coating technique. The crystalline structures, surface and magnetic properties of the films has been investigated by an X-ray diffractometer (XRD), a field emission scanning electron microscope (FESEM), an atomic force microscope (AFM) and a vibrating sample magnetometer (VSM). The XRD analysis revealed that the films have garnet structure. The lattice parameter increased as Ce content was increased up to 0.25 due to the Ce~(3+) ions completely substituted for Y~(3+) ions. For films x ≥ 0.3, the lattice parameter decreased. The FESEM results showed that the average grains were small, ranging from 11 to 14 nm and the thickness of films increased with the increment of Ce contents. VSM results for both in and out-plane magnetic measurement showed the film with x=0 has the highest saturation magnetization (M_s) values. With the increment of Ce contents, the Ms of films decreased due to the substitution of Ce~(3+), Dy~(3+) ions in the c-site. For films x ≥ 0.3 the reduction of M_s values was due to the presence of CeO_2 in the film. The films with x=0-0.25 exhibited increases in H_c values. The improvement of coercivity value, small grain size and high crystalline structure of film with x=0.25 has a potential to be used in magneto optical (MO) memory storage applications.