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

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).

arXiv comment9 pages, 4 figures

References in corpus (17)

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• High frequency ESR investigation on dynamical charge disproportionation and spin gap excitation in NaV_2O_5
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• Dzyaloshinskii-Moriya interaction in NaV${}_2$O${}_5$: a microscopic study

Cited by in corpus (9)

• Electrodynamics of Correlated Electron Materials
• First-principles investigation of symmetric and antisymmetric exchange interactions of SrCu${}_2$(BO${}_3$)${}_2$
• High Field Specific Heat of 2D Quantum Spin System SrCu2(BO3)2
• Far-infrared spectroscopy of spin excitations and Dzyaloshinskii-Moriya interactions in a Shastry-Sutherland compound SrCu${}_2$(BO${}_3$)$_2
• Magnon Dispersion and Anisotropies in SrCu${}_2$(BO${}_3$)${}_2$
• High-field spectroscopy of singlet-triplet transitions in the spin-dimer systems Sr3Cr2O8 and Ba3Cr2O8
• Magneto-optic far-infrared study of Sr${}_{14}$Cu${}_{24}$O${}_{41}$: triplet excitations in chains
• Triplons, triplon pairs and dynamical symmetries in laser-driven Shastry-Sutherland magnets
• Triplet excitations in the frustrated spin ladder Li${}_2$Cu${}_2$O(SO${}_4$)${}_2$