Initial Atomic Motion Immediately Following Femtosecond-Laser Excitation in Phase-Change Materials

E. Matsubara, S. Okada, T. Ichitsubo, T. Kawaguchi, A. Hirata, P. F. Guan, K. Tokuda, K. Tanimura, T. Matsunaga, M. W. Chen, N. Yamada

研究成果: ジャーナルへの寄稿記事

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Despite the fact that phase-change materials are widely used for data storage, no consensus exists on the unique mechanism of their ultrafast phase change and its accompanied large and rapid optical change. By using the pump-probe observation method combining a femtosecond optical laser and an x-ray free-electron laser, we substantiate experimentally that, in both GeTe and Ge2Sb2Te5 crystals, rattling motion of mainly Ge atoms takes place with keeping the off-center position just after femtosecond-optical-laser irradiation, which eventually leads to a higher symmetry or disordered state. This very initial rattling motion in the undistorted lattice can be related to instantaneous optical change due to the loss of resonant bonding that characterizes GeTe-based phase change materials. Based on the amorphous structure derived by first-principles molecular dynamics simulation, we infer a plausible ultrafast amorphization mechanism via nonmelting.

元の言語英語
記事番号135501
ジャーナルPhysical Review Letters
117
発行部数13
DOI
出版物ステータス出版済み - 9 21 2016
外部発表Yes

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All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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