title: Terahertz spectroscopy of spin waves in multiferroic BiFeO3 in high magnetic fields.
abstract: We have studied the magnetic field dependence of far-infrared active magnetic modes in a single ferroelectric domain BiFeO3 crystal at low temperature. The modes soften close to the critical field of 18.8 T along the [001] (pseudocubic) axis, where the cycloidal structure changes to the homogeneous canted antiferromagnetic state and a new strong mode with linear field dependence appears that persists at least up to 31 T. A microscopic model that includes two Dzyaloshinskii-Moriya interactions and easy-axis anisotropy describes closely both the zero-field spectroscopic modes as well as their splitting and evolution in a magnetic field. The good agreement of theory with experiment suggests that the proposed model provides the foundation for future technological applications of this multiferroic material.
authors.affiliation: National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia. urmas.nagel@kbfi.ee
authors.forename: U
authors.initials: U
authors.lastname: Nagel
authors.forename: Randy S
authors.initials: RS
authors.lastname: Fishman
authors.forename: T
authors.initials: T
authors.lastname: Katuwal
authors.forename: H
authors.initials: H
authors.lastname: Engelkamp
authors.forename: D
authors.initials: D
authors.lastname: Talbayev
authors.forename: Hee Taek
authors.initials: HT
authors.lastname: Yi
authors.forename: S-W
authors.initials: SW
authors.lastname: Cheong
authors.forename: T
authors.initials: T
authors.lastname: Rõõm