Low-energy optical sum-rule in moiré graphene
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arXiv
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| Format: | Preprint |
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2023
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| _version_ | 1866915004805021696 |
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| author | Mendez-Valderrama, J. F. Mao, Dan Chowdhury, Debanjan |
| author_facet | Mendez-Valderrama, J. F. Mao, Dan Chowdhury, Debanjan |
| contents | Few layers of graphene at small twist-angles have emerged as a fascinating platform for studying the problem of strong interactions in regimes with a nearly quenched single-particle kinetic energy and non-trivial band topology. Starting from the strong-coupling limit of twisted bilayer graphene with a vanishing single-electron bandwidth and interlayer-tunneling between the same sublattice sites, we present an {\it exact} analytical theory of the Coulomb interaction-induced low-energy optical spectral weight at all {\it integer} fillings. In this limit, while the interaction-induced single-particle dispersion is finite, the optical spectral weight vanishes identically at integer fillings. We study corrections to the optical spectral weight by systematically including the effects of experimentally relevant strain-induced renormalization of the single-electron bandwidth and interlayer tunnelings between the same sublattice sites. Given the relationship between the optical spectral weight and the diamagnetic response that controls superconducting $T_c$, our results highlight the relative importance of specific parent insulating phases in enhancing the tendency towards superconductivity when doped away from integer fillings. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2312_03819 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Low-energy optical sum-rule in moiré graphene Mendez-Valderrama, J. F. Mao, Dan Chowdhury, Debanjan Strongly Correlated Electrons Mesoscale and Nanoscale Physics Superconductivity Few layers of graphene at small twist-angles have emerged as a fascinating platform for studying the problem of strong interactions in regimes with a nearly quenched single-particle kinetic energy and non-trivial band topology. Starting from the strong-coupling limit of twisted bilayer graphene with a vanishing single-electron bandwidth and interlayer-tunneling between the same sublattice sites, we present an {\it exact} analytical theory of the Coulomb interaction-induced low-energy optical spectral weight at all {\it integer} fillings. In this limit, while the interaction-induced single-particle dispersion is finite, the optical spectral weight vanishes identically at integer fillings. We study corrections to the optical spectral weight by systematically including the effects of experimentally relevant strain-induced renormalization of the single-electron bandwidth and interlayer tunnelings between the same sublattice sites. Given the relationship between the optical spectral weight and the diamagnetic response that controls superconducting $T_c$, our results highlight the relative importance of specific parent insulating phases in enhancing the tendency towards superconductivity when doped away from integer fillings. |
| title | Low-energy optical sum-rule in moiré graphene |
| topic | Strongly Correlated Electrons Mesoscale and Nanoscale Physics Superconductivity |
| url | https://arxiv.org/abs/2312.03819 |