Superconductivity from spin fluctuations and long-range interactions in magic-angle twisted bilayer graphene

Fuente: arXiv
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Auteurs principaux: Braz, Lauro B., Martins, George B., da Silva, Luis G. G. V. Dias
Format: Preprint
Publié: 2023
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author Braz, Lauro B.
Martins, George B.
da Silva, Luis G. G. V. Dias
author_facet Braz, Lauro B.
Martins, George B.
da Silva, Luis G. G. V. Dias
contents Magic-angle twisted bilayer graphene (MATBG) has been extensively explored both theoretically and experimentally as a suitable platform for a rich and tunable phase diagram that includes ferromagnetism, charge order, broken symmetries, and unconventional superconductivity. In this work, we investigate the intricate interplay between long-range electron-electron interactions, spin fluctuations, and superconductivity in MATBG. By employing a low-energy model for MATBG that captures the correct shape of the flat bands, we explore the effects of short- and long-range interactions on spin fluctuations and their impact on the superconducting (SC) pairing vertex in the Random Phase Approximation (RPA). We find that the SC state is notably influenced by the strength of long-range Coulomb interactions. Interestingly, our RPA calculations indicate that there is a regime where the system can traverse from a magnetic phase to the SC phase by \emph{increasing} the relative strength of long-range interactions compared to the on-site ones. These findings underscore the relevance of electron-electron interactions in shaping the intriguing properties of MATBG and offer a pathway for designing and controlling its SC phase.
format Preprint
id arxiv_https___arxiv_org_abs_2309_02178
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Superconductivity from spin fluctuations and long-range interactions in magic-angle twisted bilayer graphene
Braz, Lauro B.
Martins, George B.
da Silva, Luis G. G. V. Dias
Mesoscale and Nanoscale Physics
Strongly Correlated Electrons
Superconductivity
Magic-angle twisted bilayer graphene (MATBG) has been extensively explored both theoretically and experimentally as a suitable platform for a rich and tunable phase diagram that includes ferromagnetism, charge order, broken symmetries, and unconventional superconductivity. In this work, we investigate the intricate interplay between long-range electron-electron interactions, spin fluctuations, and superconductivity in MATBG. By employing a low-energy model for MATBG that captures the correct shape of the flat bands, we explore the effects of short- and long-range interactions on spin fluctuations and their impact on the superconducting (SC) pairing vertex in the Random Phase Approximation (RPA). We find that the SC state is notably influenced by the strength of long-range Coulomb interactions. Interestingly, our RPA calculations indicate that there is a regime where the system can traverse from a magnetic phase to the SC phase by \emph{increasing} the relative strength of long-range interactions compared to the on-site ones. These findings underscore the relevance of electron-electron interactions in shaping the intriguing properties of MATBG and offer a pathway for designing and controlling its SC phase.
title Superconductivity from spin fluctuations and long-range interactions in magic-angle twisted bilayer graphene
topic Mesoscale and Nanoscale Physics
Strongly Correlated Electrons
Superconductivity
url https://arxiv.org/abs/2309.02178