Dresden 2009 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 22: Brownian motion and transport II
DY 22.4: Talk
Thursday, March 26, 2009, 11:00–11:15, ZEU 118
Classical and quantum spin pumps — •Fredy Leonardo Dubeibe Marin1,2,3, Thomas Dittrich1,2, and Klaus Richter3 — 1Universidad Nacional de Colombia, Departamento de Fisica, Bogota D.C., Colombia — 2CeiBA -- Complejidad, Bogota D.C., Colombia — 3Institut für Theoretische Physik Universität Regensburg, Regensburg, Germany
Chaotic scattering with an internal degree of freedom and the possibility to generate directed transport of angular momentum in such a system is studied in a specific model, a magnetic dipole moving in periodically modulated magnetic field confined to a compact region in space. We show that this system is an irregular scatterer in large parts of its parameter space. If in addition all spatio-temporal symmetries are broken, directed transport of mass as well as angular momentum occurs. The sensitive parameter dependence of the corresponding currents includes frequent sign reversals. Zeros of either current quantity correspond to the exclusive occurrence of the other and thus give rise in particular to angular-momentum separation without mass transport as a classical analogue of spin-polarized currents. For the quantum case, we sketch the theory for spins and indicate how to extend our classical results in this context. Employing Floquet scattering theory we show that the basic mechanism responsible for the separation of spins in the classical case carries over to the quantum level, thus giving rise to a spin pump capable of generating polarized spin currents.