Evidence for superconductivity in Li-decorated monolayer graphene.
Monolayer graphene exhibits many spectacular electronic properties, with superconductivity being arguably the most notable exception. It was theoretically proposed that superconductivity might be induced by enhancing the electron-phonon coupling through the decoration of graphene with an alkali adatom superlattice [Profeta G, Calandra M, Mauri F (2012) Nat Phys 8(2):131-134]. Although experiments have shown an adatom-induced enhancement of the electron-phonon coupling, superconductivity has never been observed. Using angle-resolved photoemission spectroscopy (ARPES), we show that lithium deposited on graphene at low temperature strongly modifies the phonon density of states, leading to an enhancement of the electron-phonon coupling of up to λ ≃ 0.58. On part of the graphene-derived π*-band Fermi surface, we then observe the opening of a Δ ≃ 0.9-meV temperature-dependent pairing gap. This result suggests for the first time, to our knowledge, that Li-decorated monolayer graphene is indeed superconducting, with Tc ≃ 5.9 K.
Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada; Quantum Matter Institute, University of British Columbia, Vancouver, BC V6T 1Z4, Canada;
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Ludbrook
Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada; Quantum Matter Institute, University of British Columbia, Vancouver, BC V6T 1Z4, Canada;
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Levy
Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada; Quantum Matter Institute, University of British Columbia, Vancouver, BC V6T 1Z4, Canada;
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Nigge
Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada; Quantum Matter Institute, University of British Columbia, Vancouver, BC V6T 1Z4, Canada;
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Zonno
Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada; Quantum Matter Institute, University of British Columbia, Vancouver, BC V6T 1Z4, Canada;
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Schneider
Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada; Quantum Matter Institute, University of British Columbia, Vancouver, BC V6T 1Z4, Canada;
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Dvorak
Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada; Quantum Matter Institute, University of British Columbia, Vancouver, BC V6T 1Z4, Canada;
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Veenstra
Quantum Matter Institute, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1, Canada;
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Zhdanovich
Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada; Quantum Matter Institute, University of British Columbia, Vancouver, BC V6T 1Z4, Canada;
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Wong
Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada; Quantum Matter Institute, University of British Columbia, Vancouver, BC V6T 1Z4, Canada;
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Dosanjh
Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany.
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Straßer
Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany.
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Stöhr
Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany.
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Forti
Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany.
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Ast
Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany.
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Starke
Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada; Quantum Matter Institute, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; damascelli@physics.ubc.ca.
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Damascelli
ARPES; graphene; superconductivity