title: THz magnetoelectric atomic rotations in the chiral compound Ba3NbFe3Si2O14.
abstract: We have determined the terahertz spectrum of the chiral langasite Ba3NbFe3Si2O14 by means of synchrotron-radiation measurements. Two excitations are revealed that are shown to have a different nature. The first one, purely magnetic, is observed at low temperature in the magnetically ordered phase and is assigned to a magnon. The second one persists far into the paramagnetic phase and exhibits both an electric and a magnetic activity at slightly different energies. This magnetoelectric excitation is interpreted in terms of atomic rotations and requires a helical electric polarization.
authors.affiliation: Institut Néel, CNRS et Université Joseph Fourier, BP166, F-38042 Grenoble Cedex 9, France.
authors.forename: L
authors.initials: L
authors.lastname: Chaix
authors.affiliation: Institut Néel, CNRS et Université Joseph Fourier, BP166, F-38042 Grenoble Cedex 9, France.
authors.forename: S
authors.initials: S
authors.lastname: de Brion
authors.affiliation: Institut Néel, CNRS et Université Joseph Fourier, BP166, F-38042 Grenoble Cedex 9, France.
authors.forename: F
authors.initials: F
authors.lastname: Lévy-Bertrand
authors.affiliation: Institut Néel, CNRS et Université Joseph Fourier, BP166, F-38042 Grenoble Cedex 9, France.
authors.forename: V
authors.initials: V
authors.lastname: Simonet
authors.affiliation: Institut Néel, CNRS et Université Joseph Fourier, BP166, F-38042 Grenoble Cedex 9, France.
authors.forename: R
authors.initials: R
authors.lastname: Ballou
authors.affiliation: Institut Néel, CNRS et Université Joseph Fourier, BP166, F-38042 Grenoble Cedex 9, France.
authors.forename: B
authors.initials: B
authors.lastname: Canals
authors.affiliation: Institut Néel, CNRS et Université Joseph Fourier, BP166, F-38042 Grenoble Cedex 9, France.
authors.forename: P
authors.initials: P
authors.lastname: Lejay
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex, France.
authors.forename: J B
authors.initials: JB
authors.lastname: Brubach
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex, France.
authors.forename: G
authors.initials: G
authors.lastname: Creff
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex, France.
authors.forename: F
authors.initials: F
authors.lastname: Willaert
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex, France.
authors.forename: P
authors.initials: P
authors.lastname: Roy
authors.affiliation: European Synchrotron Radiation Facility, 6 rue Jules Horowitz, BP 220, 38043 Grenoble, France.
authors.forename: A
authors.initials: A
authors.lastname: Cano