Ultrafast pump-probe measurements of short small-polaron lifetimes in the mixed-valence perovskite Cs${}_{2}$Au${}_{2}$I${}_{6}$ under high pressures

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Ultrafast pump-probe measurements of short small-polaron lifetimes in the mixed-valence perovskite Cs $_{2}$ Au $_{2}$ I $_{6}$ under high pressures

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

Phys. Rev. B 85, 081102(R) – Published 3 February 2012

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 intervalence charge transfer plays an important role in the structural transition.

Received 28 December 2011

DOI:https://doi.org/10.1103/PhysRevB.85.081102

Authors & Affiliations

M. Trigo^1,2,*, J. Chen^1,2, M. P. Jiang^1,2, W. L. Mao^2,3, S. C. Riggs^2,4, M. C. Shapiro^2,4, I. R. Fisher^2,4, and D. A. Reis^1,2,5

¹Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
²Stanford Institute for Materials and Energy Science, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025
³Department of Geological & Environmental Sciences, Stanford University, Stanford, California 94305, USA
⁴Department of Applied Physics and Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
⁵Department of Photon Science and Applied Physics, Stanford University, Stanford, California 94305, USA

^*mtrigo@slac.stanford.edu

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Vol. 85, Iss. 8 — 15 February 2012

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