Effective model for Majorana modes in graphene

It was recently proposed that the interface between a graphene nanoribbon in the canted antiferromagnetic quantum Hall state and an s-wave superconductor may present topological superconductivity, resulting in the appearance of Majorana zero modes [1]. However, a description of the low-energy physics in terms of system parameters was still missing. Starting from a mean-field continuum model for graphene in proximity to a superconductor, we derive the low-energy effective Hamiltonian describing the interface of this heterojunction from first principles. A comparison between tight-binding simulations and analytical calculations with effective masses suggests that normal reflections at the interface must be considered in order to fully describe the low-energy physics.

[1] P. San-Jose, J. L. Lado, R. Aguado, F. Guinea, and J. Fernández-Rossier, Phys. Rev. X 5, 041042 (2015).