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Parity forbidden excitations of Sr2CuO2Cl2 revealed by optical third-harmonic spectroscopy

A. B. Schumacher·J. S. Dodge·M. A. Carnahan·R. A. Kaindl·D. S. Chemla·L. L. Miller
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Abstract

We present the first study of nonlinear optical third harmonic generation in the strongly correlated charge-transfer insulator Sr2CuO2Cl2. For fundamental excitation in the near-infrared, the THG spectrum reveals a strongly resonant response for photon energies near 0.7 eV. Polarization analysis reveals this novel resonance to be only partially accounted for by three-photon excitation to the optical charge-transfer exciton, and indicates that an even-parity excitation at 2 eV, with a_1g symmetry, participates in the third harmonic susceptibility.

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A. B. Schumacher, J. S. Dodge, M. A. Carnahan, R. A. Kaindl, D. S. Chemla, L. L. Miller. 2001-05-25. Parity forbidden excitations of Sr2CuO2Cl2 revealed by optical third-harmonic spectroscopy. https://doi.org/10.1103/physrevlett.87.127006

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