Abstract
The objective of the study was to investigate effect of ferromagnetic layer growth temperature on exchange bias of BiFeO3/FePt bi-layer epitaxial films. In this paper, we prepared the BiFeO3 (10 nm) / FePt (10 nm) thin films were epitaxially grown on (111) SrTiO3 (STO) single crystal substrates and systemically study effect of deposition temperature of FePt. The formation of epitaxial films structure was confirmed from the x-ray diffraction and (00L) Bragg reflection of x-ray. A slight partial relaxation of out-of-plane strain in epitaxial systems was observed. Synchrotron radiation XRD results display clear sixfold symmetries and (111) FePt/BiFeO3 films by using (002) azimuthal scan, unambiguously indicating that the present samples were epitaxially thin films. Large exchange field (Heb) of 54－412Oe at room temperature were obtained for the epitaxial (111) BiFeO3 (10 nm) / FePt (10 nm) films at different growth temperatures (300 – 700 ºC). With regard to temperature of FePt, there was a large EB value for the samples with FePt temperature at endpoint. As FePt temperature excesses the blocking temperature, the Heb decreases dramatically. The effect of surface morphology of BiFeO3 layers on Heb in the present samples was also investigated.