Highly tunable band structure in ferroelectric R-stacked bilayer WSe$_2$
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arXiv
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| Auteurs principaux: | , , , , , , , , |
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| Format: | Preprint |
| Publié: |
2025
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| _version_ | 1866911136215990272 |
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| author | Li, Zhe Thor, Prokhor Kourmoulakis, George Ivanova, Tatyana V. Taniguchi, Takashi Watanabe, Kenji Yu, Hongyi Brotons-Gisbert, Mauro Gerardot, Brian D. |
| author_facet | Li, Zhe Thor, Prokhor Kourmoulakis, George Ivanova, Tatyana V. Taniguchi, Takashi Watanabe, Kenji Yu, Hongyi Brotons-Gisbert, Mauro Gerardot, Brian D. |
| contents | Transition metal dichalcogenide homobilayers unite two frontiers of quantum materials research: sliding ferroelectricity, arising from rhombohedral (R) stacking, and moiré quantum matter, emerging from small-angle twisting. The spontaneous polarization of ferroelectric R-stacked homobilayers produces a highly tunable band structure, which, together with strain-induced piezoelectricity, governs the topology and correlated electronic phases of twisted bilayers. Here we present a systematic low-temperature optical spectroscopy study of R-stacked bilayer WSe$_2$ to quantitatively establish its fundamental electronic and ferroelectric properties. Exciton and exciton-polaron spectroscopy under doping reveals a pronounced electron-hole asymmetry that confirms type-II band alignment, with the conduction and valence band edges located at the $Λ$ and K valleys, respectively. Through distinct excitonic responses and tunable interlayer-intralayer exciton hybridization under displacement fields, we uncover the coexistence of AB and BA ferroelectric domains. Using exciton-polarons as a probe, we directly measure the intrinsic polarization field and extract the interlayer potential. Finally, we demonstrate electric-field-driven symmetric switching of the valence band maximum, attributed to ferroelectric domain switching. These results provide a complete experimental picture of the band alignment, spontaneous polarization field, and domain dynamics of R-stacked WSe$_2$, establishing key parameters to understand twisted bilayers and enabling new ferroelectric and excitonic device opportunities. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2509_02886 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Highly tunable band structure in ferroelectric R-stacked bilayer WSe$_2$ Li, Zhe Thor, Prokhor Kourmoulakis, George Ivanova, Tatyana V. Taniguchi, Takashi Watanabe, Kenji Yu, Hongyi Brotons-Gisbert, Mauro Gerardot, Brian D. Materials Science Superconductivity Transition metal dichalcogenide homobilayers unite two frontiers of quantum materials research: sliding ferroelectricity, arising from rhombohedral (R) stacking, and moiré quantum matter, emerging from small-angle twisting. The spontaneous polarization of ferroelectric R-stacked homobilayers produces a highly tunable band structure, which, together with strain-induced piezoelectricity, governs the topology and correlated electronic phases of twisted bilayers. Here we present a systematic low-temperature optical spectroscopy study of R-stacked bilayer WSe$_2$ to quantitatively establish its fundamental electronic and ferroelectric properties. Exciton and exciton-polaron spectroscopy under doping reveals a pronounced electron-hole asymmetry that confirms type-II band alignment, with the conduction and valence band edges located at the $Λ$ and K valleys, respectively. Through distinct excitonic responses and tunable interlayer-intralayer exciton hybridization under displacement fields, we uncover the coexistence of AB and BA ferroelectric domains. Using exciton-polarons as a probe, we directly measure the intrinsic polarization field and extract the interlayer potential. Finally, we demonstrate electric-field-driven symmetric switching of the valence band maximum, attributed to ferroelectric domain switching. These results provide a complete experimental picture of the band alignment, spontaneous polarization field, and domain dynamics of R-stacked WSe$_2$, establishing key parameters to understand twisted bilayers and enabling new ferroelectric and excitonic device opportunities. |
| title | Highly tunable band structure in ferroelectric R-stacked bilayer WSe$_2$ |
| topic | Materials Science Superconductivity |
| url | https://arxiv.org/abs/2509.02886 |