Effect of Inversion Asymmetry on Bilayer Graphene's Superconducting and Exciton Condensates

Fuente: arXiv
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Autori principali: Hu, Xiang, Rossi, Enrico, Barlas, Yafis
Natura: Preprint
Pubblicazione: 2023
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author Hu, Xiang
Rossi, Enrico
Barlas, Yafis
author_facet Hu, Xiang
Rossi, Enrico
Barlas, Yafis
contents Inversion asymmetry in bilayer graphene can be tuned by the displacement field. As a result, the band dispersion in biased bilayer graphene acquires flat band regions near the Dirac points along with a non-trivial band geometry. We analyze the effect of inversion symmetry on the critical temperature and superfluid stiffness of the superconducting state of AB-stacked graphene bilayer and on the exciton condensate in double layers formed by two AB-stacked graphene bilayers. The geometric superfluid stiffness in bilayer graphene superconductors is found to be negligible due to the small superconducting gap. Furthermore, we show that the geometric superfluid stiffness is maximized for a constant order parameter. Therefore, it can be neglected in biased bilayer graphene superconductors with any pairing symmetry. However, the displacement field enhances the geometric superfluid stiffness in exciton condensates. It is most prominent at low densities and high displacement fields. A consequence of the geometric superfluid stiffness is a modest enhancement of the Berezinskii-Kosterlitz-Thouless transition temperature in bilayer graphene's exciton condensate.
format Preprint
id arxiv_https___arxiv_org_abs_2304_04825
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Effect of Inversion Asymmetry on Bilayer Graphene's Superconducting and Exciton Condensates
Hu, Xiang
Rossi, Enrico
Barlas, Yafis
Mesoscale and Nanoscale Physics
Superconductivity
Inversion asymmetry in bilayer graphene can be tuned by the displacement field. As a result, the band dispersion in biased bilayer graphene acquires flat band regions near the Dirac points along with a non-trivial band geometry. We analyze the effect of inversion symmetry on the critical temperature and superfluid stiffness of the superconducting state of AB-stacked graphene bilayer and on the exciton condensate in double layers formed by two AB-stacked graphene bilayers. The geometric superfluid stiffness in bilayer graphene superconductors is found to be negligible due to the small superconducting gap. Furthermore, we show that the geometric superfluid stiffness is maximized for a constant order parameter. Therefore, it can be neglected in biased bilayer graphene superconductors with any pairing symmetry. However, the displacement field enhances the geometric superfluid stiffness in exciton condensates. It is most prominent at low densities and high displacement fields. A consequence of the geometric superfluid stiffness is a modest enhancement of the Berezinskii-Kosterlitz-Thouless transition temperature in bilayer graphene's exciton condensate.
title Effect of Inversion Asymmetry on Bilayer Graphene's Superconducting and Exciton Condensates
topic Mesoscale and Nanoscale Physics
Superconductivity
url https://arxiv.org/abs/2304.04825