Quasiperiodic pairing in graphene quasicrystals

Fuente: arXiv
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Auteurs principaux: Ghadimi, Rasoul, Yang, Bohm-Jung
Format: Preprint
Publié: 2024
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author Ghadimi, Rasoul
Yang, Bohm-Jung
author_facet Ghadimi, Rasoul
Yang, Bohm-Jung
contents We investigate the superconducting instabilities of twisted bilayer graphene quasicrystals (TBGQC) obtained by stacking two monolayer graphene sheets with a $30^\circ$ relative twisting. The electronic energy spectrum of TBGQC contains periodic energy ranges (PER) and quasiperiodic energy ranges (QER), where the underlying local density of states (LDOS) exhibits periodic and quasiperiodic distribution, respectively. We found that superconductivity in the PER is a simple superposition of two monolayer superconductors. This is because, particularly near the charge neutrality point of TBGQC, the two layers are weekly coupled, leading to pairing instabilities with uniform distribution in real space. On the other hand, within QER, the inhomogeneous distribution of the LDOS enhances the superconducting instability with a non-uniform distribution of pairing amplitudes, leading to quasiperiodic superconductivity. Our study can qualitatively explain the superconductivity in recently discovered moiré quasicrystals, which show superconductivity in its QER.
format Preprint
id arxiv_https___arxiv_org_abs_2408_05714
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Quasiperiodic pairing in graphene quasicrystals
Ghadimi, Rasoul
Yang, Bohm-Jung
Superconductivity
Mesoscale and Nanoscale Physics
We investigate the superconducting instabilities of twisted bilayer graphene quasicrystals (TBGQC) obtained by stacking two monolayer graphene sheets with a $30^\circ$ relative twisting. The electronic energy spectrum of TBGQC contains periodic energy ranges (PER) and quasiperiodic energy ranges (QER), where the underlying local density of states (LDOS) exhibits periodic and quasiperiodic distribution, respectively. We found that superconductivity in the PER is a simple superposition of two monolayer superconductors. This is because, particularly near the charge neutrality point of TBGQC, the two layers are weekly coupled, leading to pairing instabilities with uniform distribution in real space. On the other hand, within QER, the inhomogeneous distribution of the LDOS enhances the superconducting instability with a non-uniform distribution of pairing amplitudes, leading to quasiperiodic superconductivity. Our study can qualitatively explain the superconductivity in recently discovered moiré quasicrystals, which show superconductivity in its QER.
title Quasiperiodic pairing in graphene quasicrystals
topic Superconductivity
Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2408.05714