Valley switch in a graphene superlattice due to pseudo-Andreev reflection

C.W.J. Beenakker, N.V. Gnezdilov, E. Dresselhaus, V.P. Ostroukh, Y. Herasymenko, I. Adagideli, J. Tworzydło

Research output: Contribution to journalArticleAcademicpeer-review

13 Citations (Scopus)

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.
Original languageEnglish
Article number241403(R)
JournalPhysical Review B
Volume97
Issue number24
DOIs
Publication statusPublished - 2018
Externally publishedYes

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