Electric field effect on BiFeO3 single crystal investigated by Raman spectroscopy

Micro-Raman spectroscopy has been used to study lattice dynamics associated with the ferroelectric domains of a BiFeO3 single crystal at low temperature. The phonon assignment shows a large frequency splitting between the transverse and longitudinal components of the A(1) phonon mode related to the Bi-O bonds in contrast with thin films where the splitting is negligible. Applying an external electric field induces frequency shifts of the low energy modes related to the Bi-O bonds. These softenings are due to a tensile stress via the piezoelectric effect. The authors give estimates of the phonon deformation potentials. (C) 2007 American Institute of Physics.