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arXiv · 0704.3632

Colossal magnon-phonon coupling in multiferroic Eu$_{0.75}$Y$_{0.25}$MnO$_3$

R. Valdés Aguilar·A. B. Sushkov·C. L. Zhang·Y. J. Choi·S. -W. Cheong·H. D. Drew
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Abstract

We report the spectra of magnetically induced electric dipole absorption in Eu$_{0.75}$Y$_{0.25}$MnO$_3$ from temperature dependent far infrared spectroscopy (10-250 cm$^{-1}$). These spectra, which occur only in the $e||a$ polarization, consist of two relatively narrow electromagnon features that onset at $T_{FE}=30$ K and a broad absorption band that persists to temperatures well above $T_N=47$ K. The observed excitations account for the step up of the static dielectric constant in the ferroelectric phase. The electromagnon at 80 cm$^{-1}$ is observed to be strongly coupled to the nearby lowest optical phonon which transfers more than 1/2 of its spectral weight to the magnon. We attribute the origin of the broad background absorption to the two magnon emission decay process of the phonon.

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R. Valdés Aguilar, A. B. Sushkov, C. L. Zhang, Y. J. Choi, S. -W. Cheong, H. D. Drew. 2007-07-24. Colossal magnon-phonon coupling in multiferroic Eu$_{0.75}$Y$_{0.25}$MnO$_3$. https://doi.org/10.1103/physrevb.76.060404

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