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Federico Mazzola: Strong electron phonon coupling in the sigma band of graphene

posted 6 Jul 2016, 02:09 by info admin
Norwegian University of Science and Technology (NTNU)

The electronic structure of graphene has attracted interest over the last few years, hosting several exotic physics phenomena such as quantum Hall effect and Berry's phase. Graphene  provides a perfect laboratory for exploring electronic correlations in a 2D system and their potential for novel applications. In this framework, many body effects play an important role affecting the electronic structure of this material and modifying the behavior of the electrons in the 2D carbon layer.

Among the many-body effects, electron phonon coupling plays an important role. This effect, has important implications for transport properties, for example in metallic conductors it is usually the main responsible for an increase of the material resistance. In addition, whilst electron-phonon coupling is primarily responsible for electrical losses in standard conductors, it is also able to give superconductivity in certain systems. However, this effect has never been thought to be possible at energy away from the Fermi level. In this work, using angle-resolved photoemission spectroscopy combined to density functional theory calculations, we show the existence of an exceptionally strong electron phonon coupling in the sigma band of graphene, away from the Fermi level. We are also able to disentangle this effect from sub lattice interference shedding light on this intriguing phenomenon and revisiting a fundamental concept in the physics of graphene which has so far remained under debate.

Federico Mazzola is a PostDoc at the Norwegian University of Science and technology (NTNU) under the supervision of Prof. Justin Wells. He got his PhD under the supervision of Prof. Justin Wells during which he studied the electronic properties of solid state systems using photoemission spectroscopy-based techniques. Previously he got his M. Physics in Condensed Matter Physics at University of Rome, La Sapienza with a thesis project carried out in Denmark at Aarhus University under the supervision of Prof. Philip Hofmann on ARPES-based studies on graphene at the synchrotron facility ASTRID (now ASTRID2) (SGM-3 beamline, Aarhus, DK). He has experiences in various synchrotron-based techniques such as Angle resolved photoemission spectroscopy (ARPES), spin-ARPES, resonant photoemission spectroscopy and X-ray photoemission spectroscopy (XPS).