Stéphane Berciaud, University of Strasbourg, France

Stephane Berciaud

I am « maître de conférences » (assistant professor) at Université de Strasbourg since 2010. I do my research at Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS). My main focus is on the optical and electronic properties of carbon nanotubes and graphene. I came to LNCMI-Grenoble for the first time in spring 2012 to perform inelastic (Raman) light scattering measurements in graphene layers under a strong transverse static magnetic field.

This project started from a very informal discussion with Clement Faugeras (CNRS researcher in Marek Potemski's group at LNMCI-G). Clément and his colleagues were the first to demonstrate interesting couplings between optical phonons and electronic excitations across Landau levels in epitaxial graphene and in graphene-like domains on the surface of bulk graphite. However, the latter effects remain elusive in mechanically exfoliated graphene layers, presumably due to substrate-induced, spatially inhomogeneous unintentional doping. On our side, we have demonstrated, by means of spatially resolved Raman scattering, that freestanding graphene layers were quasi-undoped. Such samples are ideally suited for magneto-Raman scattering measurements. 

We have performed two very encouraging runs (one week each) on single and few-layer graphene samples, during which we have observed distinct signatures of magneto-phonon resonances and electronic Raman scattering. These studies help uncover the intrinsic properties of low-energy electronic excitations in graphene layers and permit to explore the impact electron-electron interactions on the electronic dispersion. 

It has been a real pleasure to discover the facilities at LNCMI and benefit from cutting-edge working conditions, in a very friendly and stimulating atmosphere. The specifically designed setup at LNCMI-G is unique and permits spatially resolved optical measurements under a strong magnetic field, with sub-micrometer resolution and repeatability. I am looking forward to my next run(s), starting with a two-week stay in July 2013.