Strain-induced effects in phase transitions in thin films of multiferroic BiFeO3 probed by optical second-harmonic generation

Optical second-harmonic generation (SHG) was applied to study the ferroelectric and magnetic properties of strained epitaxial BiFeO, films deposited on (001) SrTiO3 substrates by metal organic chemical vapor deposition. A strong interplay between the ferroelectric and magnetic subsystems of bismuth ferrite films results in the pronounced temperature dependence of the SHG intensity. The decrease of the critical temperature of the ferroelectric phase transition and the expansion of the nonlinear transient area near Neel temperature were observed for the strained BiFeO3 films.