Polarized Raman spectroscopy of nearly-tetragonal BiFeO3 thin films
Abstract
BiFeO3 thin films can be epitaxially stabilized in a nearly-tetragonal phase under a high biaxial compressive strain. Here we investigate the polarized Raman spectra of constrained BiFeO3 films with tetragonal-like (BFO-T), rhombohedral-like (BFO-R) and multiphase (BFO-T+R) structure. Based on analysis of the number and symmetry of the Raman lines, we provide strong experimental evidence that the nearly-tetragonal films are monoclinic (Cc symmetry) and not tetragonal (P4mm). Through the Raman mapping technique we show localized coexistence of BFO-T and BFO-R phases with the relative fraction dependent on the film thickness.
0