TY - JOUR
T1 - Enhancement of electron-phonon coupling in Cs-overlayered intercalated bilayer graphene
AU - Kleeman, J.
AU - Sugawara, K.
AU - Sato, T.
AU - Takahashi, T.
N1 - Publisher Copyright:
© 2016 IOP Publishing Ltd.
Copyright:
Copyright 2018 Elsevier B.V., All rights reserved.
PY - 2016/4/21
Y1 - 2016/4/21
N2 - We have performed high-resolution angle-resolved photoemission spectroscopy (ARPES) on cesium (Cs) intercalated bilayer graphene with a Cs overlayer (Cs-C8CsC8). Low-energy electron diffraction shows a (2 × 2) pattern consistent with intercalation of a Cs layer similar to bulk C8Cs, in addition to the signature of a nearly commensurate superstructure created by the Cs overlayer. ARPES results reveal folding of the π bands due to the periodic (2 × 2) potential of the intercalated Cs atoms, together with a free-electron-like state at the point. Significant mass renormalization is observed in the band dispersion near the Fermi level, indicative of strong electron-phonon coupling. Based on analysis of the self-energy, we find anisotropic electron-phonon coupling with an estimated strength of ± 0.02 in the K- direction, and in the K-M direction. This coupling is much larger than that of other doped graphenes, and comparable to superconducting bulk GICs. We attribute this large electron-phonon coupling constant to the presence of the Cs overlayer, which highly dopes bands, and creates a structure similar to stage-I graphite intercalation compounds.
AB - We have performed high-resolution angle-resolved photoemission spectroscopy (ARPES) on cesium (Cs) intercalated bilayer graphene with a Cs overlayer (Cs-C8CsC8). Low-energy electron diffraction shows a (2 × 2) pattern consistent with intercalation of a Cs layer similar to bulk C8Cs, in addition to the signature of a nearly commensurate superstructure created by the Cs overlayer. ARPES results reveal folding of the π bands due to the periodic (2 × 2) potential of the intercalated Cs atoms, together with a free-electron-like state at the point. Significant mass renormalization is observed in the band dispersion near the Fermi level, indicative of strong electron-phonon coupling. Based on analysis of the self-energy, we find anisotropic electron-phonon coupling with an estimated strength of ± 0.02 in the K- direction, and in the K-M direction. This coupling is much larger than that of other doped graphenes, and comparable to superconducting bulk GICs. We attribute this large electron-phonon coupling constant to the presence of the Cs overlayer, which highly dopes bands, and creates a structure similar to stage-I graphite intercalation compounds.
KW - ARPES
KW - electronphonon coupling
KW - grapheme
KW - graphite intercalation compounds
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U2 - 10.1088/0953-8984/28/20/204001
DO - 10.1088/0953-8984/28/20/204001
M3 - Article
AN - SCOPUS:84970003851
VL - 28
JO - Journal of Physics Condensed Matter
JF - Journal of Physics Condensed Matter
SN - 0953-8984
IS - 20
M1 - 204001
ER -