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Large gap electron-hole superfluidity and shape resonances in coupled graphene nanoribbons

We predict enhanced electron-hole superfluidity in two coupled electron-hole armchair-edge terminated graphene nanoribbons separated by a thin insulating barrier. In contrast to graphene monolayers, the multiple subbands of the nanoribbons are parabolic at low energy with a gap between the conductio...

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Autores principales: Zarenia, M., Perali, A., Peeters, F. M., Neilson, D.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4843006/
https://www.ncbi.nlm.nih.gov/pubmed/27108968
http://dx.doi.org/10.1038/srep24860
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author Zarenia, M.
Perali, A.
Peeters, F. M.
Neilson, D.
author_facet Zarenia, M.
Perali, A.
Peeters, F. M.
Neilson, D.
author_sort Zarenia, M.
collection PubMed
description We predict enhanced electron-hole superfluidity in two coupled electron-hole armchair-edge terminated graphene nanoribbons separated by a thin insulating barrier. In contrast to graphene monolayers, the multiple subbands of the nanoribbons are parabolic at low energy with a gap between the conduction and valence bands, and with lifted valley degeneracy. These properties make screening of the electron-hole interaction much weaker than for coupled electron-hole monolayers, thus boosting the pairing strength and enhancing the superfluid properties. The pairing strength is further boosted by the quasi one-dimensional quantum confinement of the carriers, as well as by the large density of states near the bottom of each subband. The latter magnifies superfluid shape resonances caused by the quantum confinement. Several superfluid partial condensates are present for finite-width nanoribbons with multiple subbands. We find that superfluidity is predominately in the strongly-coupled BEC and BCS-BEC crossover regimes, with large superfluid gaps up to 100 meV and beyond. When the gaps exceed the subband spacing, there is significant mixing of the subbands, a rounding of the shape resonances, and a resulting reduction in the one-dimensional nature of the system.
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spelling pubmed-48430062016-04-29 Large gap electron-hole superfluidity and shape resonances in coupled graphene nanoribbons Zarenia, M. Perali, A. Peeters, F. M. Neilson, D. Sci Rep Article We predict enhanced electron-hole superfluidity in two coupled electron-hole armchair-edge terminated graphene nanoribbons separated by a thin insulating barrier. In contrast to graphene monolayers, the multiple subbands of the nanoribbons are parabolic at low energy with a gap between the conduction and valence bands, and with lifted valley degeneracy. These properties make screening of the electron-hole interaction much weaker than for coupled electron-hole monolayers, thus boosting the pairing strength and enhancing the superfluid properties. The pairing strength is further boosted by the quasi one-dimensional quantum confinement of the carriers, as well as by the large density of states near the bottom of each subband. The latter magnifies superfluid shape resonances caused by the quantum confinement. Several superfluid partial condensates are present for finite-width nanoribbons with multiple subbands. We find that superfluidity is predominately in the strongly-coupled BEC and BCS-BEC crossover regimes, with large superfluid gaps up to 100 meV and beyond. When the gaps exceed the subband spacing, there is significant mixing of the subbands, a rounding of the shape resonances, and a resulting reduction in the one-dimensional nature of the system. Nature Publishing Group 2016-04-25 /pmc/articles/PMC4843006/ /pubmed/27108968 http://dx.doi.org/10.1038/srep24860 Text en Copyright © 2016, Macmillan Publishers Limited http://creativecommons.org/licenses/by/4.0/ This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/
spellingShingle Article
Zarenia, M.
Perali, A.
Peeters, F. M.
Neilson, D.
Large gap electron-hole superfluidity and shape resonances in coupled graphene nanoribbons
title Large gap electron-hole superfluidity and shape resonances in coupled graphene nanoribbons
title_full Large gap electron-hole superfluidity and shape resonances in coupled graphene nanoribbons
title_fullStr Large gap electron-hole superfluidity and shape resonances in coupled graphene nanoribbons
title_full_unstemmed Large gap electron-hole superfluidity and shape resonances in coupled graphene nanoribbons
title_short Large gap electron-hole superfluidity and shape resonances in coupled graphene nanoribbons
title_sort large gap electron-hole superfluidity and shape resonances in coupled graphene nanoribbons
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4843006/
https://www.ncbi.nlm.nih.gov/pubmed/27108968
http://dx.doi.org/10.1038/srep24860
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