Electric field effect on BiFeO$_3$ single crystal investigated by Raman spectroscopy

TL;DR

This study uses micro-Raman spectroscopy to explore how an external electric field influences lattice vibrations and ferroelectric domain behavior in BiFeO$_3$ single crystals, revealing significant phonon frequency shifts and stress effects.

Contribution

It provides new insights into the electric field-induced phonon shifts and stress effects in BiFeO$_3$ single crystals, with detailed phonon deformation potential estimates.

Findings

Large frequency splitting between transverse and longitudinal A$_1$ phonons in single crystals

Electric field induces phonon softening related to Bi-O bonds

Tensile stress from the piezoelectric effect causes observed phonon shifts

Abstract

Micro-Raman spectroscopy has been used to study lattice dynamics associated with the ferroelectric domains of a BiFeO$_3$ 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. We give estimates of the phonon deformation potentials.