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arXiv · 0906.3059

Model for twin electromagnons and magnetically induced oscillatory polarization in multiferroic RMnO$_3$

Markku P. V. Stenberg·Rogerio de Sousa
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Abstract

We propose a model for the pair of electromagnon excitations observed in the class of multiferroic materials {\it R}MnO$_3$ ({\it R} is a rare-earth ion). The model is based on a harmonic cycloid ground state interacting with a zone-edge magnon and its twin excitation separated in momentum space by two times the cycloid wave vector. The pair of electromagnons is activated by cross coupling between magnetostriction and spin-orbit interactions. Remarkably, the spectral weight of the twin electromagnon is directly related to the presence of a magnetically induced oscillatory polarization in the ground state. This leads to the surprising prediction that TbMnO$_3$ has an oscillatory polarization with amplitude 50 times larger than its uniform polarization.

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Markku P. V. Stenberg, Rogerio de Sousa. 2009-09-24. Model for twin electromagnons and magnetically induced oscillatory polarization in multiferroic RMnO$_3$. https://doi.org/10.1103/physrevb.80.094419

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