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Theory of phonon-assisted "forbidden" optical transitions in spin-gapped systems

Olivier Cepas·Timothy Ziman
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Abstract

We consider the absorption of light with emission of one S(tot)=1 magnetic excitation in systems with a spin gap induced by quantum fluctuations. We argue that an electric dipole transition is allowed on the condition that a virtual phonon instantaneously breaks the inversion symmetry. We derive an effective operator for the transition and argue that the proposed theory explains the polarized experiments in CuGeO(3) and SrCu(2)[BO(3)](2).

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Olivier Cepas, Timothy Ziman. 2004-01-14. Theory of phonon-assisted "forbidden" optical transitions in spin-gapped systems. https://doi.org/10.1103/physrevb.70.024404

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