Valley switch in a graphene superlattice due to pseudo-Andreev reflection
Abstract
Dirac electrons in graphene have a valley degree of freedom that is being explored as a carrier of information. In that context of "valleytronics" one seeks to coherently manipulate the valley index. Here we show that reflection from a superlattice potential can provide a valley switch: Electrons approaching a pristine-graphene--superlattice-graphene interface near normal incidence are reflected in the opposite valley. We identify the topological origin of this valley switch, by mapping the problem onto that of Andreev reflection from a topological superconductor, with the electron-hole degree of freedom playing the role of the valley index. The valley switch is ideal at a symmetry point of the superlattice potential, but remains close to 100% in a broad parameter range.
Keywords
Cite
@article{arxiv.1805.02487,
title = {Valley switch in a graphene superlattice due to pseudo-Andreev reflection},
author = {C. W. J. Beenakker and N. V. Gnezdilov and E. Dresselhaus and V. P. Ostroukh and Y. Herasymenko and I. Adagideli and J. Tworzydlo},
journal= {arXiv preprint arXiv:1805.02487},
year = {2018}
}
Comments
5 pages, 4 figures (published version, "Editor's suggestion")