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Environmental control of electron-phonon coupling in barium doped graphene

Authors/others:Verbitskiy, N. I. (Universität zu Köln) Fedorov, A. V. (Universität zu Köln) Tresca, C. (Universita degli Studi dell Aquila) Profeta, G. (Universita degli Studi dell Aquila) Petaccia, L. (Elettra Sincrotrone Trieste) Senkovskiy, B. V. (Universität zu Köln) Usachov, D. Yu (Saint Petersburg State University) Vyalikh, D. V. (Saint Petersburg State University) Yashina, L. V. (Lomonosov Moscow State University (MSU)) Eliseev, A. A. (Lomonosov Moscow State University (MSU)) Pichler, T.Grüneis, A. (Universität zu Köln)
Abstract:Two-dimensional superconductivity in alkali-and alkaline-Earth-metal doped monolayer graphene has been explained in the framework of electron-phonon coupling (EPC) and experiments yielded superconducting transition temperatures (TC) up to 6 K. In contrast to bulk graphite intercalation compounds, the interface of doped graphene with its environment affects its physical properties. Here we present a novel and well-defined BaC8 interface structure in Ba-doped single-layer graphene on Au and Ge substrates. We use angle-resolved photoemission spectroscopy in combination with ab initio modelling to extract the Eliashberg function and EPC for both substrates. This allows us to quantitatively assess the environmental effects for both Au and Ge substrates on superconductivity in graphene. We show that for semiconducting Ge substrates, the doping level and EPC are higher. Our study highlights that both dopant order and the metallicity of the substrate can be used to control EPC and hence superconductivity.
Number of pages:7
Date of publication:12.2016
Journal title:2D Materials
Digital Object Identifier (DOI):http://dx.doi.org/10.1088/2053-1583/3/4/045003
Publication Type:Article
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