Structural contribution to light-induced gap suppression in Ta$_2$NiSe$_5$
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arXiv
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| Auteurs principaux: | , , , , , , , , , , , , , , , |
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| Format: | Preprint |
| Publié: |
2025
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| _version_ | 1866912543484674048 |
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| author | Chen, Zijing Xu, Chenhang Xie, Chendi Tang, Weichen Liu, Qiaomei Wu, Dong Xu, Qing Jiang, Tao Zhu, Pengfei Zou, Xiao Li, Jun Wang, Zhiwei Wang, Nanlin Qian, Dong Zong, Alfred Xiang, Dao |
| author_facet | Chen, Zijing Xu, Chenhang Xie, Chendi Tang, Weichen Liu, Qiaomei Wu, Dong Xu, Qing Jiang, Tao Zhu, Pengfei Zou, Xiao Li, Jun Wang, Zhiwei Wang, Nanlin Qian, Dong Zong, Alfred Xiang, Dao |
| contents | An excitonic insulator is a material that hosts an exotic ground state, where an energy gap opens due to spontaneous condensation of bound electron-hole pairs. Ta$_2$NiSe$_5$ is a promising candidate for this type of material, but the coexistence of a structural phase transition with the gap opening has led to a long-standing debate regarding the origin of the insulating gap. Here we employ MeV ultrafast electron diffraction to obtain quantitative insights into the atomic displacements in Ta$_2$NiSe$_5$ following photoexcitation, which has been overlooked in previous time-resolved spectroscopy studies. In conjunction with first-principles calculations using the measured atomic displacements, we find that the structural change can largely account for the photoinduced reduction in the energy gap without considering excitonic effects. Our work illustrates the importance of a quantitative reconstruction of individual atomic pathways during nonequilibrium phase transitions, paving the way for a mechanistic understanding of a diverse array of phase transitions in correlated materials where lattice dynamics can play a pivotal role. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2508_12363 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Structural contribution to light-induced gap suppression in Ta$_2$NiSe$_5$ Chen, Zijing Xu, Chenhang Xie, Chendi Tang, Weichen Liu, Qiaomei Wu, Dong Xu, Qing Jiang, Tao Zhu, Pengfei Zou, Xiao Li, Jun Wang, Zhiwei Wang, Nanlin Qian, Dong Zong, Alfred Xiang, Dao Materials Science Strongly Correlated Electrons An excitonic insulator is a material that hosts an exotic ground state, where an energy gap opens due to spontaneous condensation of bound electron-hole pairs. Ta$_2$NiSe$_5$ is a promising candidate for this type of material, but the coexistence of a structural phase transition with the gap opening has led to a long-standing debate regarding the origin of the insulating gap. Here we employ MeV ultrafast electron diffraction to obtain quantitative insights into the atomic displacements in Ta$_2$NiSe$_5$ following photoexcitation, which has been overlooked in previous time-resolved spectroscopy studies. In conjunction with first-principles calculations using the measured atomic displacements, we find that the structural change can largely account for the photoinduced reduction in the energy gap without considering excitonic effects. Our work illustrates the importance of a quantitative reconstruction of individual atomic pathways during nonequilibrium phase transitions, paving the way for a mechanistic understanding of a diverse array of phase transitions in correlated materials where lattice dynamics can play a pivotal role. |
| title | Structural contribution to light-induced gap suppression in Ta$_2$NiSe$_5$ |
| topic | Materials Science Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2508.12363 |