Magnetic quantum ratchet effect in graphene

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.

Tarasenko, S. A.Russian Academy of Sciences (författare)
Olbrich, P.Universität Regensburg,University of Regensburg (författare)
Karch, J.Universität Regensburg,University of Regensburg (författare)
Hirmer, M.Universität Regensburg,University of Regensburg (författare)
Muller, F.Universität Regensburg,University of Regensburg (författare)
Gmitra, M.Universität Regensburg,University of Regensburg (författare)
Fabian, J.Universität Regensburg,University of Regensburg (författare)
Yakimova, R.Linköpings universitet,Linköping University (författare)
Lara Avila, Samuel,1983Chalmers tekniska högskola,Chalmers University of Technology(Swepub:cth)larsavil (författare)
Kubatkin, Sergey,1959Chalmers tekniska högskola,Chalmers University of Technology(Swepub:cth)kubatkin (författare)
Wang, M.Rice University (författare)
Vajtai, R.Rice University (författare)
Ajayan, P. M.Rice University (författare)
Kono, J.Rice University (författare)
Ganichev, S. D.Universität Regensburg,University of Regensburg (författare)
Universität RegensburgRussian Academy of Sciences (creator_code:org_t)

Av författaren/redakt...: Drexler, C.; Tarasenko, S. A.; Olbrich, P.; Karch, J.; Hirmer, M.; Muller, F.; visa fler...; Gmitra, M.; Fabian, J.; Yakimova, R.; Lara Avila, Samu ...; Kubatkin, Sergey ...; Wang, M.; Vajtai, R.; Ajayan, P. M.; Kono, J.; Ganichev, S. D.; visa färre...

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