Magnetoelectric excitations in multiferroic Ni3TeO6

The spin-order-induced ferroelectric antiferromagnet $\mathrm{N}{\mathrm{i}}₃\mathrm{Te}{\mathrm{O}}₆$ transcends the magnetoelectric performance of all other single-phase multiferroics because it exhibits nonhysteretic colossal magnetoelectric coupling [Y. S. Oh, S. Artyukhin, J. J. Yang, V. Zapf, J. W. Kim, D. Vanderbilt, and S.-W. Cheong, Nat Commun. 5, 3201 (2014)]. We investigated spin and lattice excitations in $\mathrm{N}{\mathrm{i}}₃\mathrm{Te}{\mathrm{O}}₆$ by a combination of infrared, Raman, and THz spectroscopies. Two spin excitations (near 13 and $35\phantom{\rule{0.28em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}1}$) were observed simultaneously in Raman and time-domain THz spectra below the N\'eel temperature ${T}_{\mathrm{N}}=53\phantom{\rule{0.28em}{0ex}}\mathrm{K}$. We propose to assign them to electromagnons, which are activated by the dynamic magnetoelectric coupling. A third magnon is seen only in the Raman spectra near $206\phantom{\rule{0.28em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}1}$.