Evidence for photoactivated defect induced dielectric anomalies in CuCL

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Abstract
Dielectric measurements of optically irradiated single crystal and composite samples of CuCl prepared and stored under carefully controlled conditions have revealed anomalies in both the capacitance and tan δ at 220 K. At low temperature the capacitance shows a peak versus increasing integrated photon flux which is interpreted as increasing photoinduced Cu° defect precipitate. The results are reproducible and correlate with earlier reports of anomalous diamagnetism (high temperature superconductivity precursor) in CuCl. The observation of a large low frequency dielectric constant in CuCl supports the existence of a low frequency (soft) phonon mode in the CuCl-Cu precipitate composite which could provide a mechanism for high temperature superconductivity.