Ultrafast Stiffening of the Lattice Potential and Metastable State Formation in 1$T$-TiSe$_2$
Fuente:
arXiv
Guardado en:
| Autores principales: | , , , , , , , , , , |
|---|---|
| Formato: | Preprint |
| Publicado: |
2025
|
| Materias: | |
| Acceso en línea: | |
| Etiquetas: |
Agregar Etiqueta
Sin Etiquetas, Sea el primero en etiquetar este registro!
|
| _version_ | 1866914618588266496 |
|---|---|
| author | Ye, Xue-Qing Liu, Hao Wu, Qi-Yi Zhang, Chen Tang, Xiao-Fang Chen, Bo Shu, Chuan-Cun Liu, Hai-Yun Duan, Yu-Xia Oppeneer, Peter M. Meng, Jian-Qiao |
| author_facet | Ye, Xue-Qing Liu, Hao Wu, Qi-Yi Zhang, Chen Tang, Xiao-Fang Chen, Bo Shu, Chuan-Cun Liu, Hai-Yun Duan, Yu-Xia Oppeneer, Peter M. Meng, Jian-Qiao |
| contents | We use ultrafast optical spectroscopy to investigate the electronic and lattice dynamics of the charge-density wave (CDW) material 1$T$-TiSe$_2$ across various temperatures and pump fluences. We reveal a close relationship between the observed ultrafast dynamical processes and two characteristic temperatures: $T_{\rm CDW}$ ($\sim$202 K) and $T^*$ ($\sim$165 K). Two coherent phonon modes are identified: a high-frequency $A_{1g}$ mode ($ω_{1}$) and a lower-frequency $A_{1g}$ CDW amplitude mode ($ω_{2}$). In stark contrast to thermal melting, where phonons soften, the CDW amplitude mode exhibits anomalous hardening (frequency upshift) with increasing pump fluence. We establish this hardening as the direct signature of an ultrafast restoration of the bare lattice potential. The photoexcited carrier plasma screens the long-range electron-phonon interactions that drive the Peierls-like instability, effectively ``undressing" the soft phonon and driving its frequency toward the stiffer value of the unrenormalized lattice. Furthermore, an abrupt increase in the excited state buildup time above a critical pump fluence marks a sharp boundary to a photoinduced metastable metallic state. These findings demonstrate that the CDW order in 1$T$-TiSe$_2$ is governed by a fragile, fluence-tunable competition between excitonic correlations and lattice dynamics. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2512_02595 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Ultrafast Stiffening of the Lattice Potential and Metastable State Formation in 1$T$-TiSe$_2$ Ye, Xue-Qing Liu, Hao Wu, Qi-Yi Zhang, Chen Tang, Xiao-Fang Chen, Bo Shu, Chuan-Cun Liu, Hai-Yun Duan, Yu-Xia Oppeneer, Peter M. Meng, Jian-Qiao Strongly Correlated Electrons We use ultrafast optical spectroscopy to investigate the electronic and lattice dynamics of the charge-density wave (CDW) material 1$T$-TiSe$_2$ across various temperatures and pump fluences. We reveal a close relationship between the observed ultrafast dynamical processes and two characteristic temperatures: $T_{\rm CDW}$ ($\sim$202 K) and $T^*$ ($\sim$165 K). Two coherent phonon modes are identified: a high-frequency $A_{1g}$ mode ($ω_{1}$) and a lower-frequency $A_{1g}$ CDW amplitude mode ($ω_{2}$). In stark contrast to thermal melting, where phonons soften, the CDW amplitude mode exhibits anomalous hardening (frequency upshift) with increasing pump fluence. We establish this hardening as the direct signature of an ultrafast restoration of the bare lattice potential. The photoexcited carrier plasma screens the long-range electron-phonon interactions that drive the Peierls-like instability, effectively ``undressing" the soft phonon and driving its frequency toward the stiffer value of the unrenormalized lattice. Furthermore, an abrupt increase in the excited state buildup time above a critical pump fluence marks a sharp boundary to a photoinduced metastable metallic state. These findings demonstrate that the CDW order in 1$T$-TiSe$_2$ is governed by a fragile, fluence-tunable competition between excitonic correlations and lattice dynamics. |
| title | Ultrafast Stiffening of the Lattice Potential and Metastable State Formation in 1$T$-TiSe$_2$ |
| topic | Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2512.02595 |