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HL: Halbleiterphysik
HL 36: Spinabh
ängiger Transport
HL 36.11: Vortrag
Donnerstag, 29. März 2001, 18:00–18:15, S2
The ballistic spin–filter transistor — •Dirk Grundler — Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung,
Universität Hamburg, Jungiusstraße 11, D–20355 Hamburg, Germany
The ballistic electron transport across the interface between a metallic ferromagnet (fm) and a semiconductor (sm) incorporating a two-dimensional electron system (2D ES) is calculated. Using the Landauer–Büttiker (LB) formalism, a well-developed theory for ballistic transport in mesoscopic 2D ES, we have introduced the concept of two independent spin currents representing the majority and minority spins. Within this two-current model, we have calculated the spin-dependent transmission probabilities and magnetoresistance. The LB theory predicts the new and fundamental aspect of spin-filtering at the single fm/sm interface [1]. The effect is pronounced for Fe on InAs. The microscopic origin is the mismatch of velocities kF/m* at the Fermi edge, where kF is the Fermi wave vector and m* is the effective mass of electrons. This band structure mismatch is spin dependent and can be tuned via a gate electrode which is on top of the semiconductor. The calculated magnetoresistance effect for the ballistic electron channel between two ferromagnetic electrodes is large and up to 5% in the spin-valve configuration [2].
Support by the DFG via SFB 508 ’Quantenmaterialien’ and the NEDO program Spin Electronics is acknowledged.
[1] D. Grundler, Phys. Rev. Lett. (accepted for publication)
[2] D. Grundler, Phys. Rev. B (Rapid Commun.) (submitted)