Electromagnon in the Y-type hexaferrite BaSrCoZnFel1Al022

We studied single crystals of BaSrCoZnFe
₁₁
AIO
₂₂
, a multiferroic with the Y-hexaferrite crystal structure. A purely electric-dipole-active electromagnon near ca. 1.2 THz was observed in time-domain terahertz and Raman spectra. The electromagnon is sensitive to applied magnetic field, and its activity can be correlated with the existence of various magnetic phases. Selection rules show that the electromagnon involves spins vibrating along the hexagonal axis c and that it is activated by exchange striction.