Effect of film thickness on structural and magnetic properties of single crystalline Ba(FeZr)O thin films on (001)SrTiO substrates

Kanatani, Hidekazu*; Matsui, Toshiyuki*; Hirao, Norie; Yamamoto, Hiroyuki; Baba, Yuji  ; Kume, Hideki*; Iwase, Akihiro*

The epitaxially grown Ba(FeZr)O (BFZO) films with various thicknesses ranging from 30 to 170 nm were successfully synthesized on (001)SrTiO substrates by a pulsed laser-beam deposition method. The results of X-ray diffraction and transmission electron microscopy showed that the lattice sonstant along the a-axis is expanded by 0.07 over 100 nm thickness. Although all the BFZO films showed ferromagnetic and dielectric natures, the magnetization values were found to be significantly dependent upon the film thickness. The magnetization values of the films with a thickness over 100 nm films were fairly decreased rather than those of the smaller thickness films. In accordance with the X-ray photoelectron spectroscopy measurement, the decrease in the magnetization was mainly ascribed to the decreased number of the tetravalent Fe ions, which was caused by the relaxation of he misfit strain between the film and substrates.