We show that the wavefunctions form caustics in circular graphene p-n junctions which in the framework of geometrical optics can be interpreted with negative refractive index.
Cite
@article{arxiv.0706.4034,
title = {Caustics due to Negative Refractive Index in Circular Graphene p-n Junctions},
author = {Jozsef Cserti and Andras Palyi and Csaba Peterfalvi},
journal= {arXiv preprint arXiv:0706.4034},
year = {2007}
}