Formation of Interface Bound States on a Graphene-Superconductor Junction in the Presence of Charge Inhomogeneities

Pablo Burset, William Javier Herrera, Alfredo Levy Yeyati

Departamento de Física Teórica de la Materia Condensada and Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, Madrid, Spain.
Departamento de Física, Universidad Nacional de Colombia, Bogotá, Colombia.

DOI: 10.4236/graphene.2013.21005                

Abstract

Interface bound states have been theoretically predicted to appear at isolated graphene-superconductor junctions. These states are formed at the interface due to the interplay between virtual Andreev and normal reflections and provide long range superconducting correlations on the graphene layer. We describe in detail the formation of these states from combining the Dirac equation with the Bogoliubov de Gennes equations of superconductivity. On the other hand, fluctuations of the low energy charge density in graphene have been confirmed as the dominating type of disorder. For analyzing the effect of disorder on these states we use a microscopic tight binding model. We show how the formation of these states is robust against the presence of disorder in the form of electron charge inhomogeneities in the graphene layer. We numerically compute the effect of disorder on the interface bound states and on the local density of states of graphene.

Keywords

Graphene; Superconducting Hybrid Structures; Andreev Reflection

Conflicts of Interest

The authors declare no conflicts of interest.

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