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Electron–Hole Crossover in Gate-Controlled Bilayer Graphene Quantum Dots

[Image: see text] Electron and hole Bloch states in bilayer graphene exhibit topological orbital magnetic moments with opposite signs, which allows for tunable valley-polarization in an out-of-plane magnetic field. This property makes electron and hole quantum dots (QDs) in bilayer graphene interest...

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Autores principales: Banszerus, L., Rothstein, A., Fabian, T., Möller, S., Icking, E., Trellenkamp, S., Lentz, F., Neumaier, D., Watanabe, K., Taniguchi, T., Libisch, F., Volk, C., Stampfer, C.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2020
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7564435/
https://www.ncbi.nlm.nih.gov/pubmed/32986437
http://dx.doi.org/10.1021/acs.nanolett.0c03227
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author Banszerus, L.
Rothstein, A.
Fabian, T.
Möller, S.
Icking, E.
Trellenkamp, S.
Lentz, F.
Neumaier, D.
Watanabe, K.
Taniguchi, T.
Libisch, F.
Volk, C.
Stampfer, C.
author_facet Banszerus, L.
Rothstein, A.
Fabian, T.
Möller, S.
Icking, E.
Trellenkamp, S.
Lentz, F.
Neumaier, D.
Watanabe, K.
Taniguchi, T.
Libisch, F.
Volk, C.
Stampfer, C.
author_sort Banszerus, L.
collection PubMed
description [Image: see text] Electron and hole Bloch states in bilayer graphene exhibit topological orbital magnetic moments with opposite signs, which allows for tunable valley-polarization in an out-of-plane magnetic field. This property makes electron and hole quantum dots (QDs) in bilayer graphene interesting for valley and spin-valley qubits. Here, we show measurements of the electron–hole crossover in a bilayer graphene QD, demonstrating opposite signs of the magnetic moments associated with the Berry curvature. Using three layers of top gates, we independently control the tunneling barriers while tuning the occupation from the few-hole regime to the few-electron regime, crossing the displacement-field-controlled band gap. The band gap is around 25 meV, while the charging energies of the electron and hole dots are between 3 and 5 meV. The extracted valley g-factor is around 17 and leads to opposite valley polarization for electrons and holes at moderate B-fields. Our measurements agree well with tight-binding calculations for our device.
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spelling pubmed-75644352020-10-19 Electron–Hole Crossover in Gate-Controlled Bilayer Graphene Quantum Dots Banszerus, L. Rothstein, A. Fabian, T. Möller, S. Icking, E. Trellenkamp, S. Lentz, F. Neumaier, D. Watanabe, K. Taniguchi, T. Libisch, F. Volk, C. Stampfer, C. Nano Lett [Image: see text] Electron and hole Bloch states in bilayer graphene exhibit topological orbital magnetic moments with opposite signs, which allows for tunable valley-polarization in an out-of-plane magnetic field. This property makes electron and hole quantum dots (QDs) in bilayer graphene interesting for valley and spin-valley qubits. Here, we show measurements of the electron–hole crossover in a bilayer graphene QD, demonstrating opposite signs of the magnetic moments associated with the Berry curvature. Using three layers of top gates, we independently control the tunneling barriers while tuning the occupation from the few-hole regime to the few-electron regime, crossing the displacement-field-controlled band gap. The band gap is around 25 meV, while the charging energies of the electron and hole dots are between 3 and 5 meV. The extracted valley g-factor is around 17 and leads to opposite valley polarization for electrons and holes at moderate B-fields. Our measurements agree well with tight-binding calculations for our device. American Chemical Society 2020-09-28 2020-10-14 /pmc/articles/PMC7564435/ /pubmed/32986437 http://dx.doi.org/10.1021/acs.nanolett.0c03227 Text en This is an open access article published under a Creative Commons Attribution (CC-BY) License (http://pubs.acs.org/page/policy/authorchoice_ccby_termsofuse.html) , which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited.
spellingShingle Banszerus, L.
Rothstein, A.
Fabian, T.
Möller, S.
Icking, E.
Trellenkamp, S.
Lentz, F.
Neumaier, D.
Watanabe, K.
Taniguchi, T.
Libisch, F.
Volk, C.
Stampfer, C.
Electron–Hole Crossover in Gate-Controlled Bilayer Graphene Quantum Dots
title Electron–Hole Crossover in Gate-Controlled Bilayer Graphene Quantum Dots
title_full Electron–Hole Crossover in Gate-Controlled Bilayer Graphene Quantum Dots
title_fullStr Electron–Hole Crossover in Gate-Controlled Bilayer Graphene Quantum Dots
title_full_unstemmed Electron–Hole Crossover in Gate-Controlled Bilayer Graphene Quantum Dots
title_short Electron–Hole Crossover in Gate-Controlled Bilayer Graphene Quantum Dots
title_sort electron–hole crossover in gate-controlled bilayer graphene quantum dots
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7564435/
https://www.ncbi.nlm.nih.gov/pubmed/32986437
http://dx.doi.org/10.1021/acs.nanolett.0c03227
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