CNR ExploRA

Articolo in rivista, 2016, ENG, 10.1088/2053-1583/3/4/045003

Environmental control of electron-phonon coupling in barium doped graphene

Verbitskiy N.I.; Fedorov A.V.; Tresca C.; Profeta G.; Petaccia L.; Senkovskiy B.V.; Usachov D.Yu.; Vyalikh D.V.; Yashina L.V.; Eliseev A.A.; Pichler T.; Gruneis A.

Faculty of Physics, University of Vienna, Strudlhofgasse 4, Vienna, A-1090, Austria; II. Physikalisches Institut, Universität zu Köln, Zülpicher Strasße 77, Cologne, D-50937, Germany; Department of Materials Science, Moscow State University, Leninskiye Gory 1/3, Moscow, 119992, Russian Federation; IFW Dresden, PO Box 270116, Dresden, D-01171, Germany; St. Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg, 199034, Russian Federation; Department of Physical and Chemical Sciences, University of L'Aquila, Via Vetoio 10, Coppito, I-67100, Italy; CNR-SPIN, Via Vetoio 10, Coppito, I-67100, Italy; Elettra Sincrotrone Trieste, Strada Statale 14 km 163.5, Trieste, I-34149, Italy; Institute of Solid State Physics, Dresden University of Technology, Helmholtzstraße 10, Dresden, D-01062, Germany; Department of Chemistry, Moscow State University, Leninskiye Gory 1/3, Moscow, 119992, Russian Federation

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 (T C ) 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.

2D materials 3 (4)