Dresden 2006 – scientific programme

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TT: Tiefe Temperaturen

TT 21: Transport: Nanoelectronics II - Spintronics and Magnetotransport - Part 2

TT 21.1: Talk

Tuesday, March 28, 2006, 16:15–16:30, HSZ 105

Coherent Spin Ratchets — •Klaus Richter, Andreas Pfund, and Dario Bercioux — Fakultät für Physik, Universität Regensburg

We propose a new class of quantum ratchet devices, namely spin-orbit based ratchets which act as sources for pure spin currents. To this end we demonstrate that the combined effect of a spatially periodic electrostatic potential, lateral confinement and spin-orbit interaction in a two-dimensional coherent conductor gives rise to a quantum ratchet mechanism for spin-polarized currents. Upon external ac-driving, and in the absence of a static bias, the system generates a directed spin current, while the total charge current is zero. We analyze the underlying mechanism by employing symmetry properties of the scattering matrix, and we numerically verify the effect for different setups relevant for experiment. We further show that the spin current directions can be changed upon tuning the Fermi energy or the relative strength of Rashba and Dresselhaus spin orbit coupling.