arXiv subjects

A. Kimouche

Publications and source records attributed to A. Kimouche.

4 recordsLinked to original sources

arXiv2022

Local work function on Graphene Nanoribbons and on the Au(111) herringbone reconstruction

Graphene nanoribbons show exciting electronic properties related to the exotic nature of the charge carriers and to local confinement as well as atomic-scale structural details. The local work function provides evidence for such structural, electronic and chemical variations at surfaces. Kelvin prove force microscopy (KPFM) can be used to measure the local contact potential difference (LCPD) between a probe tip and a surface, related to the work function. Here we use this technique to map the LCPD of graphene nanoribbons grown on a Au(111) substrate. The LCPD data shows charge transfer between the graphene nanoribbons and the gold substrate. Our results are corroborated with density functional theory calculations which verify that the maps reflect from the doping of nanoribbons. Our results help to understand the relation between atomic structures and electronic properties.

cond-mat.mes-hall↗

arXiv2014

Ripples and Charge Puddles in Graphene on a Metallic Substrate

Graphene on a dielectric substrate exhibits spatial doping inhomogeneities, forming electron-hole puddles. Understanding and controlling the latter is of crucial importance for unraveling many of graphene's fundamental properties at the Dirac point. Here we show the coexistence and correlation of charge puddles and topographic ripples in graphene decoupled from the metallic substrate it was grown on. The analysis of interferences of Dirac fermion-like electrons yields a linear dispersion relation, indicating that graphene on a metal can recover its intrinsic electronic properties.

cond-mat.mes-hall↗

arXiv2014

Cobalt intercalation at the graphene/iridium(111) interface: influence of rotational domains, wrinkles and atomic steps

Using low-energy electron microscopy, we study Co intercalation under graphene grown on Ir(111). Depending on the rotational domain of graphene on which it is deposited, Co is found intercalated at different locations. While intercalated Co is observed preferentially at the substrate step edges below certain rotational domains, it is mostly found close to wrinkles below other domains. These results indicate that curved regions (near substrate atomic steps and wrinkles) of the graphene sheet facilitate Co intercalation and suggest that the strength of the graphene/Ir interaction determines which pathway is energetically more favorable.

cond-mat.mtrl-sci↗

arXiv2014

Induced Superconductivity in Graphene Grown on Rhenium

We report a new way to strongly couple graphene to a superconductor. The graphene monolayer has been grown directly on top of a superconducting Re(0001) thin film and characterized by scanning tunneling microscopy and spectroscopy. We observed a moiré pattern due to the mismatch between Re and graphene lattice parameters that we have simulated with ab initio calculations. The density of states around the Fermi energy appears to be position dependent on this moiré pattern. Tunneling spectroscopy performed at 50 mK shows that the superconducting behavior of graphene on Re is well described by the Bardeen-Cooper-Schrieffer theory and stands for a very good interface between the graphene and its metallic substrate.

cond-mat.mes-hall↗