Substrate tuning of the structural and electronic transition in thin flakes of the excitonic insulator candidate Ta$_2$NiSe$_5$
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| Main Authors: | , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866914200613289984 |
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| author | Zhang, Yuan-Shan Yang, Zichen Xiao, Chuanlian Isobe, Masahiko Minola, Matteo Takagi, Hidenori Huang, Dennis |
| author_facet | Zhang, Yuan-Shan Yang, Zichen Xiao, Chuanlian Isobe, Masahiko Minola, Matteo Takagi, Hidenori Huang, Dennis |
| contents | Ta$_2$NiSe$_5$ continues to draw interest for its 326 K phase transition, whose dual electronic and structural nature reflects a complex interplay of electron-hole (excitonic) and electron-lattice interactions. Most studies that have attempted to decipher the relative importance of these interactions, particularly through charge transfer, have been limited to bulk samples. We utilized a thin-flake approach to modify the excitonic interactions in Ta$_2$NiSe$_5$ via an underlying film of Au. Using polarized Raman spectroscopy, we found that four layers of Ta$_2$NiSe$_5$ supported on conducting Au show a transition temperature that is both reduced by over 100 K and broadened due to an interfacial charge gradient effect, manifesting the presence of excitonic interactions. In contrast, four layers of Ta$_2$NiSe$_5$ supported on insulating Al$_2$O$_3$ show nearly bulk-like properties. We also report the development of an all-dry exfoliation and transfer protocol that generalizes substrate engineering for strongly correlated van der Waals materials. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2512_12439 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Substrate tuning of the structural and electronic transition in thin flakes of the excitonic insulator candidate Ta$_2$NiSe$_5$ Zhang, Yuan-Shan Yang, Zichen Xiao, Chuanlian Isobe, Masahiko Minola, Matteo Takagi, Hidenori Huang, Dennis Strongly Correlated Electrons Ta$_2$NiSe$_5$ continues to draw interest for its 326 K phase transition, whose dual electronic and structural nature reflects a complex interplay of electron-hole (excitonic) and electron-lattice interactions. Most studies that have attempted to decipher the relative importance of these interactions, particularly through charge transfer, have been limited to bulk samples. We utilized a thin-flake approach to modify the excitonic interactions in Ta$_2$NiSe$_5$ via an underlying film of Au. Using polarized Raman spectroscopy, we found that four layers of Ta$_2$NiSe$_5$ supported on conducting Au show a transition temperature that is both reduced by over 100 K and broadened due to an interfacial charge gradient effect, manifesting the presence of excitonic interactions. In contrast, four layers of Ta$_2$NiSe$_5$ supported on insulating Al$_2$O$_3$ show nearly bulk-like properties. We also report the development of an all-dry exfoliation and transfer protocol that generalizes substrate engineering for strongly correlated van der Waals materials. |
| title | Substrate tuning of the structural and electronic transition in thin flakes of the excitonic insulator candidate Ta$_2$NiSe$_5$ |
| topic | Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2512.12439 |