A1 Journal article (refereed)
Flat-band superconductivity in periodically strained graphene : mean-field and Berezinskii–Kosterlitz–Thouless transition (2020)

Peltonen, T. J., & Heikkilä, T. T. (2020). Flat-band superconductivity in periodically strained graphene : mean-field and Berezinskii–Kosterlitz–Thouless transition. Journal of Physics: Condensed Matter, 32(36), Article 365603. https://doi.org/10.1088/1361-648X/ab8b9d

JYU authors or editors

Publication details

All authors or editors: Peltonen, Teemu Juhani; Heikkilä, Tero T.

Journal or series: Journal of Physics: Condensed Matter

ISSN: 0953-8984

eISSN: 1361-648X

Publication year: 2020

Volume: 32

Issue number: 36

Article number: 365603

Publisher: Institute of physics

Publication country: United Kingdom

Publication language: English

DOI: https://doi.org/10.1088/1361-648X/ab8b9d

Publication open access: Not open

Publication channel open access:

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/68731

Publication is parallel published: https://arxiv.org/abs/1910.06671

Abstract

In the search of high-temperature superconductivity one option is to focus on increasing the density of electronic states. Here we study both the normal and s-wave superconducting state properties of periodically strained graphene, which exhibits approximate flat bands with a high density of states, with the flatness tunable by the strain profile. We generalize earlier results regarding a one-dimensional harmonic strain to arbitrary periodic strain fields, and further extend the results by calculating the superfluid weight and the Berezinskii–Kosterlitz–Thouless (BKT) transition temperature T BKT to determine the true transition point. By numerically solving the self-consistency equation, we find a strongly inhomogeneous superconducting order parameter, similarly to twisted bilayer graphene. In the flat-band regime the order parameter magnitude, critical chemical potential, critical temperature, superfluid weight, and BKT transition temperature are all approximately linear in the interaction strength, which suggests that high-temperature superconductivity might be feasible in this system. We especially show that by using realistic strain strengths T BKT can be made much larger than in twisted bilayer graphene, if using similar interaction strengths. We also calculate properties such as the local density of states that could serve as experimental fingerprints for the presented model.

Keywords: nanostructures; graphene; superconductivity

Free keywords: BCS theory; flat bands; graphene; strain engineering; superconductivity

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Ministry reporting: Yes

Reporting Year: 2020

JUFO rating: 2