Magnetic quantum ratchet effect in graphene
2013 (English)In: Nature Nanotechnology, ISSN 1748-3387, Vol. 8, no 2, 104-107 p.Article in journal (Refereed) Published
A periodically driven system with spatial asymmetry can exhibit a directed motion facilitated by thermal or quantum fluctuations(1). This so-called ratchet effect(2) has fascinating ramifications in engineering and natural sciences(3-18). Graphene(19) is nominally a symmetric system. Driven by a periodic electric field, no directed electric current should flow. However, if the graphene has lost its spatial symmetry due to its substrate or adatoms, an electronic ratchet motion can arise. We report an experimental demonstration of such an electronic ratchet in graphene layers, proving the underlying spatial asymmetry. The orbital asymmetry of the Dirac fermions is induced by an in-plane magnetic field, whereas the periodic driving comes from terahertz radiation. The resulting magnetic quantum ratchet transforms the a.c. power into a d.c. current, extracting work from the out-of-equilibrium electrons driven by undirected periodic forces. The observation of ratchet transport in this purest possible two-dimensional system indicates that the orbital effects may appear and be substantial in other two-dimensional crystals such as boron nitride, molybdenum dichalcogenides and related heterostructures. The measurable orbital effects in the presence of an in-plane magnetic field provide strong evidence for the existence of structure inversion asymmetry in graphene.
Place, publisher, year, edition, pages
Nature Publishing Group , 2013. Vol. 8, no 2, 104-107 p.
Engineering and Technology
IdentifiersURN: urn:nbn:se:liu:diva-90081DOI: 10.1038/nnano.2012.231ISI: 000315178800017OAI: oai:DiVA.org:liu-90081DiVA: diva2:612416
Funding Agencies|German Research Foundation (DFG)|SPP 1459GRK 1570SFB 689|European Union through ConceptGraphene||International Bureau of the Federal Ministry of Education and Research (BMBF) at the German Aerospace Center (DLR)||Russian Foundation for Basic Research (RFBR)||Russian Federation|MD-2062.2012.2|Dynasty Foundation||2013-03-212013-03-192014-11-27