Nonstandard Hubbard model and electron pairing
- URL: http://arxiv.org/abs/2307.16737v3
- Date: Tue, 30 Apr 2024 09:37:56 GMT
- Title: Nonstandard Hubbard model and electron pairing
- Authors: M. Zendra, F. Borgonovi, G. L. Celardo, S. Gurvitz,
- Abstract summary: We present a non-standard Hubbard model applicable to arbitrary single-particle potential profiles and inter-particle interactions.
Our investigation demonstrates that long-range inter-particle interactions can induce a novel mechanism for repulsive particle pairing.
These findings carry significant implications for various phenomena, including the formation of flat bands, the emergence of superconductivity in twisted bilayer graphene, and the possibility of a novel metal-insulator transition.
- Score: 0.0
- License: http://creativecommons.org/licenses/by/4.0/
- Abstract: We present a non-standard Hubbard model applicable to arbitrary single-particle potential profiles and inter-particle interactions. Our approach involves a novel treatment of Wannier functions, free from the ambiguities of conventional methods and applicable to finite systems without periodicity constraints. To ensure the consistent evaluation of Wannier functions, we develop a perturbative approach, utilizing the barrier penetration coefficient as a perturbation parameter. With the newly defined Wannier functions as a basis, we derive the Hubbard Hamiltonian, revealing the emergence of density-induced and pair tunneling terms alongside standard contributions. Our investigation demonstrates that long-range inter-particle interactions can induce a novel mechanism for repulsive particle pairing. This mechanism relies on the effective suppression of single-particle tunneling due to density-induced tunneling. Contrary to expectations based on the standard Hubbard model, an increase in inter-particle interaction does not lead to an insulating state. Instead, our proposed mechanism implies the coherent motion of correlated electron pairs, similar to bound states within a multi-well system, resistant to decay from single-electron tunneling transitions. These findings carry significant implications for various phenomena, including the formation of flat bands, the emergence of superconductivity in twisted bilayer graphene, and the possibility of a novel metal-insulator transition.
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