We investigated static and dynamic magnetoelectric properties of single crystalline ${\mathrm{BaSrCoZnFe}}_{11}{\mathrm{AlO}}_{22}$, which is a room-temperature multiferroic with Y-type hexaferrite crystal structure. Below 300 K, a purely electric-dipole-active electromagnon at $\approx 1.2$ THz with the electric polarization oscillating along the hexagonal axis was observed by THz and Raman spectroscopies. We investigated the behavior of the electromagnon with applied dc magnetic field and linked its properties to static measurements of the magnetic structure. Our analytical calculations determined selection rules for electromagnons activated by the magnetostriction mechanism in various magnetic structures of Y-type hexaferrite. Comparison with our experiment supports that the electromagnon is indeed activated by the magnetostriction mechanism involving spin vibrations along the hexagonal axis.

• Received 19 December 2017
• Revised 14 February 2018

DOI:https://doi.org/10.1103/PhysRevB.97.134406