Magnetic quantum ratchet effect in graphene
Journal article, 2013

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.




flux quanta



C. Drexler

University of Regensburg

S. A. Tarasenko

Russian Academy of Sciences

P. Olbrich

University of Regensburg

J. Karch

University of Regensburg

M. Hirmer

University of Regensburg

F. Muller

University of Regensburg

M. Gmitra

University of Regensburg

J. Fabian

University of Regensburg

R. Yakimova

Linköping University

Samuel Lara Avila

Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics

Sergey Kubatkin

Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics

M. Wang

Rice University

R. Vajtai

Rice University

P. M. Ajayan

Rice University

J. Kono

Rice University

S. D. Ganichev

University of Regensburg

Nature Nanotechnology

1748-3387 (ISSN)

Vol. 8 2 104-107

Subject Categories

Physical Sciences



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7/4/2018 1