Berlin 2012 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 13: Transport: Poster Session

TT 13.23: Poster

Monday, March 26, 2012, 15:00–19:00, Poster B

Spin polarized transport through noncollinear single-electron spin-valve transistors — •Stephan Lindebaum and Jürgen König — Theoretische Physik, Universität Duisburg-Essen and CeNIDE, D-47048 Duisburg

We study the electronic transport through a noncollinear single-electron spin-valve transistor, i.e., a metallic island with a continuous electron density of states tunnel coupled to two ferromagnetic leads. The polarization directions of the ferromagnets enclose an arbitrary angle. In the considered system, charging and spin effects play an important role and influence the transport behavior of the transistor. Furthermore, the interplay of Coulomb interaction and tunnel coupling to spin-polarized leads yields a many-body exchange field, in which the accumulated island spin precesses.

We derive kinetic equations for the island charge and spin within a diagrammatic real-time transport formalism. In our theory we perform a perturbative analysis of the transport properties up to first order in the tunnel-coupling strength (sequential-tunneling limit), which is reasonable due to the weak island-lead coupling.

Our formalism enables to analyze both the linear and nonlinear transport regimes. The electric current through the transistor and the accumulated island spin are considered in detail. In particular, we find that the exchange field can give rise to a high sensitivity of the island’s spin orientation on the gate voltage.
S. Lindebaum and J. König, arXiv:1109.5800v1