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arXiv · 0707.1054

Softening of the insulating phase near Tc for the photo-induced insulator-to-metal phase transition in vanadium dioxide

D. J. Hilton·R. P. Prasankumar·S. Fourmaux·A. Cavalleri·D. Brassard·M. A. El Khakani·J. C. Kieffer·A. J. Taylor·R. D. Averitt
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Abstract

We use optical-pump terahertz-probe spectroscopy to investigate the near-threshold behavior of the photoinduced insulator-to-metal (IM) transition in vanadium dioxide thin films. Upon approaching Tc a reduction in the fluence required to drive the IM transition is observed, consistent with a softening of the insulating state due to an increasing metallic volume fraction (below the percolation limit). This phase coexistence facilitates the growth of a homogeneous metallic conducting phase following superheating via photoexcitation. A simple dynamic model using Bruggeman effective medium theory describes the observed initial condition sensitivity.

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D. J. Hilton, R. P. Prasankumar, S. Fourmaux, A. Cavalleri, D. Brassard, M. A. El Khakani, J. C. Kieffer, A. J. Taylor, R. D. Averitt. 2007-10-17. Softening of the insulating phase near Tc for the photo-induced insulator-to-metal phase transition in vanadium dioxide. https://doi.org/10.1103/physrevlett.100.019906

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