Detecting topological currents in graphene superlattices
Abstract
Topological materials may exhibit Halllike currents flowing transversely to the applied electric field even in the absence of a magnetic field. In graphene superlattices, which have broken inversion symmetry, topological currents originating from graphene’s two valleys are predicted to flow in opposite directions and combine to produce longrange charge neutral flow. We observed this effect as a nonlocal voltage at zero magnetic field in a narrow energy range near Dirac points at distances as large as several micrometers away from the nominal current path. Locally, topological currents are comparable in strength with the applied current, indicating large valleyHall angles. The longrange character of topological currents and their transistorlike control by means of gate voltage can be exploited for information processing based on valley degrees of freedom.
 Publication:

Science
 Pub Date:
 October 2014
 DOI:
 10.1126/science.1254966
 arXiv:
 arXiv:1409.0113
 Bibcode:
 2014Sci...346..448G
 Keywords:

 PHYSICS;
 Condensed Matter  Mesoscale and Nanoscale Physics
 EPrint:
 19 pgs, 9 fgs