Direct observation of ultrafast amorphous-amorphous transitions indicated by bond stretching and angle bending in phase-change material GeTe
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arXiv
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| Main Authors: | , , , , , , , , , , , , |
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| Format: | Preprint |
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2026
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| _version_ | 1866917351347191808 |
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| author | Qi, Yingpeng Chen, Nianke Zhou, Zhihui Xu, Qing Lv, Yang Zou, Xiao Jiang, Tao Zhu, Pengfei Zhu, Min Chen, Dongxue Sun, Zhenrong Li, Xianbin Xiang, Dao |
| author_facet | Qi, Yingpeng Chen, Nianke Zhou, Zhihui Xu, Qing Lv, Yang Zou, Xiao Jiang, Tao Zhu, Pengfei Zhu, Min Chen, Dongxue Sun, Zhenrong Li, Xianbin Xiang, Dao |
| contents | The intrinsic nature of glass states and glass transitions at the atomic scale remain a fundamental open question in condensed-matter physics and materials science. By combining femtosecond electron diffraction with time-dependent density-functional theory molecular dynamics simulations, we directly observe ultrafast amorphous-amorphous transitions in amorphous GeTe, manifested as rapid Ge-Te (Ge) bond stretching within 0.2 ps and subsequent angle bending of the Ge-Te (Ge)-Ge motif on a 0.5-2 ps timescale. Critically, the ultrafast bond stretching is accompanied by localized oscillation modes with the frequency of 3.10 THz, unambiguously signaling the local Peierls-like bonding structure and the flexibility of these polarized bonds. These ultrafast collective atomic motions provide a direct structural origin for the boson peak and pay the way for systematic optimization of relaxation and crystallization kinetics. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2603_17400 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Direct observation of ultrafast amorphous-amorphous transitions indicated by bond stretching and angle bending in phase-change material GeTe Qi, Yingpeng Chen, Nianke Zhou, Zhihui Xu, Qing Lv, Yang Zou, Xiao Jiang, Tao Zhu, Pengfei Zhu, Min Chen, Dongxue Sun, Zhenrong Li, Xianbin Xiang, Dao Materials Science The intrinsic nature of glass states and glass transitions at the atomic scale remain a fundamental open question in condensed-matter physics and materials science. By combining femtosecond electron diffraction with time-dependent density-functional theory molecular dynamics simulations, we directly observe ultrafast amorphous-amorphous transitions in amorphous GeTe, manifested as rapid Ge-Te (Ge) bond stretching within 0.2 ps and subsequent angle bending of the Ge-Te (Ge)-Ge motif on a 0.5-2 ps timescale. Critically, the ultrafast bond stretching is accompanied by localized oscillation modes with the frequency of 3.10 THz, unambiguously signaling the local Peierls-like bonding structure and the flexibility of these polarized bonds. These ultrafast collective atomic motions provide a direct structural origin for the boson peak and pay the way for systematic optimization of relaxation and crystallization kinetics. |
| title | Direct observation of ultrafast amorphous-amorphous transitions indicated by bond stretching and angle bending in phase-change material GeTe |
| topic | Materials Science |
| url | https://arxiv.org/abs/2603.17400 |