Electromagnons in a ferromagnet TbMnO3 after a polarization flop
B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine 47 Nauky Ave., Kharkiv 61103, Ukraine
Received April 27, 2018, revised June 19, 2018
The electromagnon spectrum in TbMnO3 after the polarization-flop, arising from the Dzyaloshinskii–Moriya interaction, has been phenomenologically analyzed. The directions of alternating electric field along and across the spontaneous electric polarization were considered. It is shown that when the direction of the electric field is along the electric polarization (a-axis) low-frequency electromagnons have two possible frequencies which are depended on the temperature. When the orientation of the electric field is along the c-axis, the calculations do not show the excitation of low-frequency electromagnons that is qualitatively consistent with the results of Raman spectrum measurements.