Multiferroic Properties of BiFeO$_{3}$ Ceramic and Thin Film and BiFeO$_{3}$ /Co/BiFeO$_{3}$ Multilayer Structure

In situ
X-ray diffraction of BiFeO
₃
(BFO) ceramic and thin film has been carried out as a function of temperature (25degC-900degC) upon heating. The BFO thin film was deposited on Pt/TiO
_x
/SiO
_x
/Si(100) substrate by radio-frequency magnetron sputtering at 650degC. BFO thin film exhibits a structural transformation from rhombohedral to cubic in the region of 700-750degC upon heating. The magnetic property of BiFeO
₃
/Co/BiFeO
₃
multilayer structure changes from diamagnetic to ferromagnetic phases with increasing thickness of Co layer. The dielectric permittivities (real and imaginary parts) of BiFeO
₃
ceramic exhibit a frequency-dependent relaxation-like behavior and its magnitude (real part) is higher than 1000 for f les 1 MHz. Surface morphology shows that the root-mean-square roughness of BFO thin film varies with sputtering power.