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arXiv · 1111.5260

Short small-polaron lifetime in the mixed-valence perovskite Cs$_2$Au$_2$I$_6$ from high-pressure pump-probe experiments

M. Trigo·J. Chen·M. P. Jiang·W. L. Mao·S. C. Riggs·M. C. Shapiro·I. R. Fisher·D. A. Reis
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Abstract

We study the ultrafast phonon response of mixed-valence perovskite Cs$_2$Au$_2$I$_6$ using pump-probe spectroscopy under high-pressure in a diamond anvil cell. We observed a remarkable softening and broadening of the Au - I stretching phonon mode with both applied pressure and photoexcitation. Using a double-pump scheme we measured a lifetime of the charge transfer excitation into single valence Au$^{2+}$ of less than 4 ps, which is an indication of the local character of the Au$^{2+}$ excitation. Furthermore, the strong similarity between the pressure and fluence dependence of the phonon softening shows that the inter-valence charge transfer plays an important role in the structural transition.

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M. Trigo, J. Chen, M. P. Jiang, W. L. Mao, S. C. Riggs, M. C. Shapiro, I. R. Fisher, D. A. Reis. 2011-11-23. Short small-polaron lifetime in the mixed-valence perovskite Cs$_2$Au$_2$I$_6$ from high-pressure pump-probe experiments. https://doi.org/10.1103/physrevb.85.081102

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