Spin And Lattice Dynamics Of Multiferroic Srmn7o12 Studied By Thz And Infrared Spectroscopies At Low Temperatures And In Magnetic Field

Multiferroic SrMn7O12 crystals arc isostructural with CaMn7O12 which is known for its unusual symmetry properties and a record-high spin-induced polarization. We studied SrMn7O12 ceramics by THz time-domain and Fourier-transform infrared spectroscopies upon varying temperature and magnetic field. In the magnetic phases, we observed spin waves gaining strength from polar phonons; thus, they are assigned to electromagnons. We discuss the observed persistence of several low-temperature vibrational modes above the high-temperature phase transition, and the impact of atomic substitution with regard to CaMn7O12.