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Phys. Rev. B 70, 144112 (2004) [11 pages]

Femtosecond time-resolved reflection spectroscopy of photoinduced ionic-neutral phase transition in TTF-CA crystals

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Katsumi Tanimura *
The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan

Received 5 September 2003; revised 28 May 2004; published 28 October 2004

We study the dynamics of photoinduced transition from ionic to neutral phases in tetrathiafulvalen- p -chloranil crystals by means of the fs time-resolved reflection spectroscopy at 6  K . We find that the phase transition consists of three sequential steps: (1) Precursor neutral regions form within 20  ps after excitation; (2) local neutral pairs aggregate to proliferate neutral clusters at 20–100  ps after excitation; (3) three-dimensional order of the neutral phase forms around 400  ps after excitation. Temporal oscillations in the reflectivity, characterized by two modes with different frequencies, are observed and assigned to impulsive acoustic phonons associated with phase transition. We discuss the mechanism of the phase transition based on these results.


©2004 The American Physical Society

URL: http://link.aps.org/doi/10.1103/PhysRevB.70.144112
DOI: 10.1103/PhysRevB.70.144112
PACS: 61.40.Ks, 78.47.+p, 73.20.Mf, 71.20.+d

* Electronic address: tanimura@sanken.osaka-u.ac.jp

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