THz Magneto-electric atomic rotations in the chiral compound Ba3NbFe3Si2O14

Laura Chaix (1) , Sophie de Brion (2) , Florence Lévy-Bertrand (2) , Virginie Simonet (2) , Rafik Ballou (2) , Benjamin Canals (3) , Pascal Lejay (4) , Jean-Blaise Brubach (5) , Gaëlle Greff (5) , Fabrice Willaert (5) , Pascale Roy (5) , Andres Cano (6)

1 NEEL - MRS - Matériaux, Rayonnements, Structure
2 NEEL - MagSup - Magnétisme et Supraconductivité
3 NEEL - TMC - Théorie de la Matière Condensée
4 NEEL - C2MA - Croissance Cristalline et MicroAnalyse
5 Ligne AILES
6 ESRF - European Synchrotron Radiation Facility

We have determined the terahertz spectrum of the chiral langasite BaNbFe3Si2O14 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 persits 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.

Mots clés: THz spectroscopy; multiferroics; Magnetoelectric effects; models; Strongly correlated electron systems

Domaines: Electrons fortement corrélés [cond-mat.str-el]

Laura Chaix, Sophie de Brion, Florence Lévy-Bertrand, Virginie Simonet, Rafik Ballou, et al.. THz Magneto-electric atomic rotations in the chiral compound Ba3NbFe3Si2O14. Physical Review Letters, 2013, 110 (15), pp.157208. ⟨10.1103/PhysRevLett.110.157208⟩. ⟨hal-00797750⟩