Theory of intrinsic acoustic plasmons in twisted bilayer graphene
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arXiv
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| Main Authors: | , , , , |
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| Format: | Preprint |
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2024
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| _version_ | 1866909305381322752 |
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| author | Cavicchi, Lorenzo Torre, Iacopo Jarillo-Herrero, Pablo Koppens, Frank H. L. Polini, Marco |
| author_facet | Cavicchi, Lorenzo Torre, Iacopo Jarillo-Herrero, Pablo Koppens, Frank H. L. Polini, Marco |
| contents | We present a theoretical study of the intrinsic plasmonic properties of twisted bilayer graphene (TBG) as a function of the twist angle $θ$ (and other microscopic parameters such as temperature and filling factor). Our calculations, which rely on the random phase approximation, take into account four crucially important effects, which are treated on equal footing: i) the layer-pseudospin degree of freedom, ii) spatial non-locality of the density-density response function, iii) crystalline local field effects, and iv) Hartree self-consistency. We show that the plasmonic spectrum of TBG displays a smooth transition from a strongly-coupled regime (at twist angles $θ\lesssim 2^{\circ}$), where the low-energy spectrum is dominated by a weakly dispersive intra-band plasmon, to a weakly-coupled regime (for twist angles $θ\gtrsim 2^{\circ}$) where an acoustic plasmon clearly emerges. This crossover offers the possibility of realizing tunable mid-infrared sub-wavelength cavities, whose vacuum fluctuations may be used to manipulate the ground state of strongly correlated electron systems. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2401_16384 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Theory of intrinsic acoustic plasmons in twisted bilayer graphene Cavicchi, Lorenzo Torre, Iacopo Jarillo-Herrero, Pablo Koppens, Frank H. L. Polini, Marco Mesoscale and Nanoscale Physics Strongly Correlated Electrons We present a theoretical study of the intrinsic plasmonic properties of twisted bilayer graphene (TBG) as a function of the twist angle $θ$ (and other microscopic parameters such as temperature and filling factor). Our calculations, which rely on the random phase approximation, take into account four crucially important effects, which are treated on equal footing: i) the layer-pseudospin degree of freedom, ii) spatial non-locality of the density-density response function, iii) crystalline local field effects, and iv) Hartree self-consistency. We show that the plasmonic spectrum of TBG displays a smooth transition from a strongly-coupled regime (at twist angles $θ\lesssim 2^{\circ}$), where the low-energy spectrum is dominated by a weakly dispersive intra-band plasmon, to a weakly-coupled regime (for twist angles $θ\gtrsim 2^{\circ}$) where an acoustic plasmon clearly emerges. This crossover offers the possibility of realizing tunable mid-infrared sub-wavelength cavities, whose vacuum fluctuations may be used to manipulate the ground state of strongly correlated electron systems. |
| title | Theory of intrinsic acoustic plasmons in twisted bilayer graphene |
| topic | Mesoscale and Nanoscale Physics Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2401.16384 |