Carbon 72, 312 (2014)
A. Ballestar, P. Esquinazi, J. Barzola-Quiquia, S. Dusari, F. Bern, R.R. da Silva, and Y. Kopelevich
Abstract
The carrier density in tens of nanometers thick graphite samples (multi-layer-graphene, MLG) has been modified by applying a gate voltage (Vg) perpendicular to the graphene planes. Surface potential microscopy shows inhomogeneities in the carrier density (n) in the sample near surface region and under different values of Vg at room temperature. Transport measurements on different MLG samples reveal that under a large enough applied electric field these regions undergo a superconducting-like transition at T ≤ 17 K. A magnetic field applied parallel or normal to the graphene layers suppresses the transition without changing appreciably the transition temperature.