Thickness dependent ferroelectric and magnetic properties of Bi0.9Gd0.1Fe0.9Co0.1O3 films prepared by RF magnetron sputtering

Bi0.9Gd0.1Fe0.9Co0.1O3 (BGFCO) films with thickness increasing from 318 to 877 nm were successfully deposited on Pt(111)/Ti/SiO2/Si(100) substrates by radio frequency magnetron sputtering. X-ray diffraction patterns demonstrated that all BGFCO films had a single perovskite-type structure with highly (012) and (024) preferred orientations regardless of the film thickness. The crystalline quality of the film was also improved with increase in film thickness. The grain sizes of BGFCO films using scanning electron microscopy analysis were monotonously increase with thickness. The ferroelectric and magnetic tests indicated that the film thickness of about 310-450 nm was an optimum thickness in our case where both the ferroelectric and ferromagnetic properties exhibit significant values consistent with the requirements for multiferroic material applications. The ferromagnetic behavior was enhanced for BGFCO film at 10 K compared to that of 300 K. The bifurcation of the field cooling and zero-field cooling magnetizations of BGFCO film in the whole temperature range from 5 to 300 K indicated the typical characteristic of a spin-glass-like behavior originating from domain wall pinning effects. The mechanisms for the effect of thickness variation on ferroelectric and ferromagnetic characteristics of BGFCO films were discussed.