Regensburg 2010 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 6: TR: Nanoelectronics II: Spintronics and Magnetotransport
TT 6.4: Vortrag
Montag, 22. März 2010, 14:45–15:00, H19
Charge ratchet from spin flip: Space-time symmetry paradox — •Sergey Smirnov1, Dario Bercioux2, Milena Grifoni1, and Klaus Richter1 — 1Institut für Theoretische Physik, Universität Regensburg, D-93040 Regensburg, Germany — 2Freiburg Institute for Advanced Studies (FRIAS) and Physikalisches Institut, Universität Freiburg, D-79104 Freiburg, Germany
Traditionally the charge ratchet effect is considered as a consequence of either the spatial symmetry breaking engineered by asymmetric periodic potentials, or time asymmetry of the driving fields. Here we demonstrate that electrically and magnetically driven quantum dissipative systems with spin-orbit interactions represent an exception from this standard idea. In contrast to the so far well established belief, a charge ratchet effect appears when both the periodic potential and driving are symmetric. We show that the source of this paradoxical charge ratchet mechanism is the coexistence of quantum dissipation with the spin flip processes induced by spin-orbit interactions [1]. The queerness of the charge ratchet current consists in the fact that this current, in contrast to early predictions for systems without spin-orbit interactions, appears even when only one energy band provides electrons for transport and no harmonic mixing is present in the driving fields. Such purely spin-orbit charge currents are controlled by the gate voltage tuning the strength of the spin-orbit coupling. This peculiarity of the effect is very attractive from the experimental point of view.
[1] S. Smirnov, D. Bercioux, M. Grifoni and K. Richter, Phys. Rev. B 80, 201310(R) (2009).