Berlin 2008 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 22: Transport: Poster Session

TT 22.56: Poster

Wednesday, February 27, 2008, 14:00–18:00, Poster B

A spin ratchet effect in dissipative systems with spin-orbit coupling — •Sergey Smirnov¹, Dario Bercioux^1,2, Milena Grifoni¹, and Klaus Richter¹ — ¹Institut für Theoretische Physik, Universität Regensburg, D-93040 Regensburg, Germany — ²Physikalische Institut, Albert-Ludwigs-Universität, D-79104 Freiburg, Germany

A possibility to generate fully polarized pure spin currents, a hot topic in modern spintronics, is studied. The idea is to create such spin currents using a spin ratchet effect if it exists. We investigate this question in an ac driven quasi-one-dimensional periodic structure with Rashba's spin-orbit interaction [1] and strong dissipative coupling to an external environment. It is analytically proven that when the quantum transport of electrons is restricted within the sub-bands below the barrier and originating from the same Bloch band, the charge transport is totally absent. In contrast we analytically show that the stationary spin current vanishes for symmetric periodic potentials while it can be finite for asymmetric ones. This confirms the existence of the spin ratchet effect in our system. Moreover, we rigorously show that for a harmonic confinement only one component of the spin current is non-zero, that is the spin current is fully polarized.

[1] S. Smirnov, D. Bercioux, and M. Grifoni, Europhys. Lett. 80, 27003 (2007).