Flat band physics in the charge-density wave state of $1T$-TaS$_2$
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arXiv
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| Auteurs principaux: | , , |
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| Format: | Preprint |
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2024
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| _version_ | 1866917707003199488 |
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| author | Dalal, Amir Ruhman, Jonathan Venderbos, Jörn W. F. |
| author_facet | Dalal, Amir Ruhman, Jonathan Venderbos, Jörn W. F. |
| contents | 1$T$-TaS$_2$ is the only insulating transition-metal dichalcogenide (TMD) with an odd number of electrons per unit cell. This insulating state is non-magnetic, making it a potential spin-liquid candidate. The unusual electronic behavior arises from a naturally occurring nearly flat mini-band, where the properties of the strongly correlated states are significantly influenced by the microscopic starting point, necessitating a detailed and careful investigation. We revisit the electronic band structure of 1$T$-TaS$_2$, starting with the tight-binding model without CDW order. Symmetry dictates the nature of spin-orbit coupling (SOC), which, unlike in the 2H TMD structure, allows for strong off-diagonal "spin-flip" terms as well as Ising SOC. Incorporating the CDW phase, we construct a 78$\times$78 tight-binding model to analyze the band structure as a function of various parameters. Our findings show that an isolated flat band is a robust feature of this model. Depending on parameters such as SOC strength and symmetry-allowed orbital splittings, the flat band can exhibit non-trivial topological classifications. These results have significant implications for the strongly correlated physics emerging from interacting electrons in the half-filled or doped flat band. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2406_18645 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Flat band physics in the charge-density wave state of $1T$-TaS$_2$ Dalal, Amir Ruhman, Jonathan Venderbos, Jörn W. F. Strongly Correlated Electrons Materials Science 1$T$-TaS$_2$ is the only insulating transition-metal dichalcogenide (TMD) with an odd number of electrons per unit cell. This insulating state is non-magnetic, making it a potential spin-liquid candidate. The unusual electronic behavior arises from a naturally occurring nearly flat mini-band, where the properties of the strongly correlated states are significantly influenced by the microscopic starting point, necessitating a detailed and careful investigation. We revisit the electronic band structure of 1$T$-TaS$_2$, starting with the tight-binding model without CDW order. Symmetry dictates the nature of spin-orbit coupling (SOC), which, unlike in the 2H TMD structure, allows for strong off-diagonal "spin-flip" terms as well as Ising SOC. Incorporating the CDW phase, we construct a 78$\times$78 tight-binding model to analyze the band structure as a function of various parameters. Our findings show that an isolated flat band is a robust feature of this model. Depending on parameters such as SOC strength and symmetry-allowed orbital splittings, the flat band can exhibit non-trivial topological classifications. These results have significant implications for the strongly correlated physics emerging from interacting electrons in the half-filled or doped flat band. |
| title | Flat band physics in the charge-density wave state of $1T$-TaS$_2$ |
| topic | Strongly Correlated Electrons Materials Science |
| url | https://arxiv.org/abs/2406.18645 |