A1 Journal article (refereed)
Mean-field theory for superconductivity in twisted bilayer graphene (2018)

Peltonen, T., Ojajärvi, R., & Heikkilä, T. (2018). Mean-field theory for superconductivity in twisted bilayer graphene. Physical Review B, 98(22), Article 220504(R). https://doi.org/10.1103/PhysRevB.98.220504

JYU authors or editors

Publication details

All authors or editors: Peltonen, Teemu; Ojajärvi, Risto; Heikkilä, Tero

Journal or series: Physical Review B

ISSN: 2469-9950

eISSN: 2469-9969

Publication year: 2018

Volume: 98

Issue number: 22

Article number: 220504(R)

Publisher: American Physical Society

Place of Publication: College Park

Publication country: United States

Publication language: English

DOI: https://doi.org/10.1103/PhysRevB.98.220504

Publication open access: Other way freely accessible online

Publication channel open access: 

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/60699

Web address where publication is available: https://arxiv.org/abs/1805.01039

Abstract

Recent experiments show how a bilayer graphene twisted around a certain magic angle becomes superconducting as it is doped into a region with approximate flat bands. We investigate the mean-field s-wave superconducting state in such a system and show how the state evolves as the twist angle is tuned, and as a function of the doping level. We argue that part of the experimental findings could well be understood to result from an attractive electron-electron interaction mediated by electron-phonon coupling, but the flat-band nature of the excitation spectrum also makes the superconductivity quite unusual. For example, as the flat-band states are highly localized around certain spots in the structure, also the superconducting order parameter becomes strongly inhomogeneous.

Keywords: superconductivity; graphene

Free keywords: superconducting gap; superconducting order parameter; superconducting phase transition

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Ministry reporting: Yes

Reporting Year: 2018

JUFO rating: 2