Phonons in the multiferroic langasite Ba$\_3$NbFe$\_3$Si$\_2$O$\_14$ : evidences for symmetry breaking

C Toulouse, M Cazayous, S De Brion +7

The chiral langasite Ba$\_3$NbFe$\_3$Si$\_2$O$\_14$ is a multiferroic compound. While its magnetic order below T$\_N$=27 K is now well characterised, its polar order is still con…