تقرير
Ultrafast charge ordering by self-amplified exciton-phonon dynamics in TiSe$_2$
| العنوان: | Ultrafast charge ordering by self-amplified exciton-phonon dynamics in TiSe$_2$ |
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| المؤلفون: | Lian, Chao, Zhang, Sheng-Jie, Hu, Shi-Qi, Guan, Meng-Xue, Meng, Sheng |
| المصدر: | Nat Commun 11, 43 (2020) |
| سنة النشر: | 2019 |
| المجموعة: | Condensed Matter Physics (Other) |
| مصطلحات موضوعية: | Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Superconductivity, Physics - Optics |
| الوصف: | The origin of charge density waves (CDW) in TiSe$_2$ has long been debated, mainly due to the difficulties in identifying the timescales of how and when the excitonic pairing and electron-phonon coupling (EPC) come into play. Without a proper time resolution and microscopic mechanism, one has to assume simultaneous appearance of CDW and periodic lattice distortions (PLD). Here, we accomplish a complete separation of exciton and PLD dynamics and unravel their interplay in the ultrafast time domain in our real-time time-dependent density functional theory simulations. We find that laser pulses knock off the exciton order and induce a homogeneous bonding-antibonding transition in the initial 20 fs, then the weakened electronic order triggers ionic movements antiparallel to the original PLD. The EPC comes into play after the initial 20~fs, and the two processes mutually amplify each other leading to a complete inversion of CDW ordering. The self-amplified dynamics reproduces the evolution of band structures in excellent agreement with ultrafast photoemission experiment. Hence we resolve the key processes in the initial dynamics of CDW that help elucidate the mechanism underlying the long debated problem. Comment: Supplementary Material Included |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1038/s41467-019-13672-7 |
| URL الوصول: | http://arxiv.org/abs/1901.00610 |
| رقم الأكسشن: | edsarx.1901.00610 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1038/s41467-019-13672-7 |
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