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Evidence for superconductivity in Li-decorated monolayer graphene

Evidence for superconductivity in Li-decorated monolayer graphene

Authors :
Douglas Wong
Giorgio Levy
Christian R. Ast
Michael Schneider
C. N. Veenstra
Carola Straßer
Pinder Dosanjh
Andrea Damascelli
Stiven Forti
Alexander Stöhr
David J. Dvorak
Ulrich Starke
Pascal Nigge
B. Ludbrook
Sergey Zhdanovich
M. Zonno
Source :
Proceedings of the National Academy of Sciences. 112:11795-11799
Publication Year :
2015
Publisher :
Proceedings of the National Academy of Sciences, 2015.

Abstract

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 et al. Nat. Phys. 8, 131-134 (2012)]. While experiments have indeed demonstrated 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 $\lambda\!\simeq\!0.58$. On part of the graphene-derived $\pi^*$-band Fermi surface, we then observe the opening of a $\Delta\!\simeq\!0.9$ meV temperature-dependent pairing gap. This result suggests for the first time, to our knowledge, that Li-decorated monolayer graphene is indeed superconducting with $T_c\!\simeq\!5.9 K$.<br />Comment: Accepted. A high-resolution version with supplementary material can be found at http://qmlab.ubc.ca/ARPES/PUBLICATIONS/Articles/Graphene_Li.pdf

Details

ISSN :
10916490 and 00278424
Volume :
112
Database :
OpenAIRE
Journal :
Proceedings of the National Academy of Sciences
Accession number :
edsair.doi.dedup.....cabfb1f37633df2781b20acaa0c5c6bc
Full Text :
https://doi.org/10.1073/pnas.1510435112