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arXiv · 0711.2733

Electrically driven spin excitation in a ferroelectric magnet DyMnO_3

N. Kida·Y. Ikebe·Y. Takahashi·J. P. He·Y. Kaneko·Y. Yamasaki·R. Shimano·T. Arima·N. Nagaosa·Y. Tokura
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Abstract

Temperature (5--250 K) and magnetic field (0--70 kOe) variations of the low-energy (1--10 meV) electrodynamics of spin excitations have been investigated for a complete set of light-polarization configurations for a ferroelectric magnet DyMnO$_3$ by using terahertz time-domain spectroscopy. We identify the pronounced absorption continuum (1--8 meV) with a peak feature around 2 meV, which is electric-dipole active only for the light $E$-vector along the a-axis. This absorption band grows in intensity with lowering temperature from the spin-collinear paraelectric phase above the ferroelectric transition, but is independent of the orientation of spiral spin plane ($bc$ or $ab$), as shown on the original $P_{\rm s}$ (ferroelectric polarization) $\parallel c$ phase as well as the magnetic field induced $P_{\rm s}\parallel a$ phase. The possible origin of this electric-dipole active band is argued in terms of the large fluctuations of spins and spin-current.

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N. Kida, Y. Ikebe, Y. Takahashi, J. P. He, Y. Kaneko, Y. Yamasaki, R. Shimano, T. Arima, N. Nagaosa, Y. Tokura. 2008-08-02. Electrically driven spin excitation in a ferroelectric magnet DyMnO_3. https://doi.org/10.1103/physrevb.78.104414

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