Pressure Dependence of Ultrafast Carrier Dynamics in Excitonic Insulator Ta$_2$NiSe$_5$
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arXiv
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| Format: | Preprint |
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2024
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| author | Arora, Vikas Muthu, Victor S Sinha, Arijit Harnagea, Luminita Waghmare, U V Sood, A K |
| author_facet | Arora, Vikas Muthu, Victor S Sinha, Arijit Harnagea, Luminita Waghmare, U V Sood, A K |
| contents | An excitonic insulator (EI) phase is a consequence of collective many-body effects where an optical band gap is formed by the condensation of electron-hole pairs or excitons. We report pressure-dependent optical pump optical probe spectroscopy of EI Ta$_2$NiSe$_5$ in an on-site in situ geometry. The fast relaxation process depicts the transition across P$_{C_1}$ $\sim$1 GPa from EI phase to a semiconductor and P$_{C_2}$ $\sim$3 GPa from a semiconductor to a semimetallic phase. The instability of the EI phase beyond P$_{C_1}$ is captured by the Rothwarf-Taylor model by incorporating the decrease of the bandgap under pressure. The pressure coefficient of the bandgap decreases, 65 meV/GPa closely agrees with the first principle calculations. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2411_18031 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Pressure Dependence of Ultrafast Carrier Dynamics in Excitonic Insulator Ta$_2$NiSe$_5$ Arora, Vikas Muthu, Victor S Sinha, Arijit Harnagea, Luminita Waghmare, U V Sood, A K Materials Science An excitonic insulator (EI) phase is a consequence of collective many-body effects where an optical band gap is formed by the condensation of electron-hole pairs or excitons. We report pressure-dependent optical pump optical probe spectroscopy of EI Ta$_2$NiSe$_5$ in an on-site in situ geometry. The fast relaxation process depicts the transition across P$_{C_1}$ $\sim$1 GPa from EI phase to a semiconductor and P$_{C_2}$ $\sim$3 GPa from a semiconductor to a semimetallic phase. The instability of the EI phase beyond P$_{C_1}$ is captured by the Rothwarf-Taylor model by incorporating the decrease of the bandgap under pressure. The pressure coefficient of the bandgap decreases, 65 meV/GPa closely agrees with the first principle calculations. |
| title | Pressure Dependence of Ultrafast Carrier Dynamics in Excitonic Insulator Ta$_2$NiSe$_5$ |
| topic | Materials Science |
| url | https://arxiv.org/abs/2411.18031 |