Dresden 2003 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

SYHN: Hybrid nanostructures

SYHN 1: Hybrid Nanostructures

SYHN 1.6: Hauptvortrag

Donnerstag, 27. März 2003, 12:05–12:45, HSZ/01

Superconductor/semiconductor and ferromagnet/semiconductor hybrids: Andreev billiards and spin dependent transport — •Dieter Weiss, J. Eroms, M. Zenger, S. Kreuzer, J. Moser, and W. Wegscheider — Universität Regensburg, Experimentelle und Angewandte Physik, 93040 Regensburg

Hybrid systems consisting of different material classes like superconductors, semiconductors or ferromagnets are interesting since they combine physical properties of the different constituents. In the presentation two of our recent experiments on superconductor/semiconductor and ferromagnet/semiconductor hybrid structures get briefly reviewed. An array of nanopatterned superconducting Nb-disks placed on a two-dimensional electron gas in InAs quantum wells establishes an experimental Andreev billiard with interesting properties [1]. While the electron/hole trajectories in the antidot array are chaotic in the presence of an applied perpendicular magnetic field the system behaves, in the limiting case of perfect Andreev reflection, like an unpatterned two-dimensional electron gas. Injection of spin polarized electrons from metallic ferromagnets into semiconductors has been proven difficult due to the different electrical conductivities of the two materials [2]. Injection across Schottky barriers is expected to lift this obstacle [3,4]. We demonstrate spin dependent transport across thin GaAs tunnel barriers [5] which provides an upper limit for spin injection into semiconductors in transport experiments.

We thank J. De Boeck and S. Borghs from IMEC for providing high quality InAs quantum wells.

[1] J. Eroms et al., Europhys. Lett. 58, 569 (2002).

[2] G. Schmidt et al., Phys. Rev. B 62, R4790 (2000).

[3] E. I. Rashba, Phys. Rev. B 62, R16267 (2000).

[4] A. Fert et al., Phys. Rev. B 64, 184420 (2001).

[5] S. Kreuzer et al., Appl. Phys. Lett. 80, 4582 (2002).