Regensburg 2007 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 28: Transport - Poster Session
TT 28.45: Poster
Donnerstag, 29. März 2007, 14:00–17:45, Poster A
Spin-orbit based ratchets for spin-polarized currents — •Manuel Strehl1, Matthias Scheid1, Dario Bercioux1,2, and Klaus Richter1 — 1Institut für Theoretische Physik, Universität Regensburg, Germany — 2Physikalisches Institut, Albert-Ludwigs-Universität, Freiburg, Germany
Spin-quantum ratchets are a new class of ratchet devices that can give rise to spin currents. The minimal setup for the spin ratchet is given by the combination of spin-orbit interaction in a coherent quantum wire with a spatially periodic electrostatic potential.
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 combining symmetry properties of the scattering matrix and a Landau-Zener approach for evaluating the probability of the spin flipping, 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 injection energy or the relative strength of Rashba and Dresselhaus spin-orbit coupling. In addition, also the dependences of the spin current as a function of the direction of the wire with respect to the crystallographic axes is considered.