Study of spin-phonon coupling in multiferroic BiFeO3 through Raman spectroscopy

Abstract

Spin-phonon coupling in multiferroic BiFeO3 single crystal is studied through temperature dependant polarized Raman spectroscopy. The phonon hardening appears at 200 K and becomes stronger below ~135 K. Clear anomalous temperature dependence of the phonon hardening near the magnetic transitions evidence the presence of a spin-phonon coupling in BiFeO3. Different phonon modes show very distinct spin-phonon coupling behaviors. Possible interpretations of the anomalous of the phonon hardening are discussed. We suggest that the phonon hardening would be correlated to spin reorientation and partially influenced by strains of Bi vacancies. © 2020