Regensburg 2004 – wissenschaftliches Programm

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MA: Magnetismus

MA 13: Poster:Schichten(1-23),Spinabh.Trsp(24-41),Exch.Bias(42-56),Spindyn.(57-67),Mikromag.(68-76),Partikel(77-90),Spinelektr.(91-97),Elektr.Theo.(98-99),Mikromag+PhasÜ+Aniso.(100-105),Magn.Mat.(106-118),Messmethod.(119-121),Obflm.+Abbverf.(122-123)

MA 13.40: Poster

Dienstag, 9. März 2004, 15:00–19:00, Bereich A

Towards a Tunneling-Spinvalve-Transistor with epitaxial Schottky-Barrier — •Thomas Hagler, Martin Dumm, and G"unther Bayreuther — Institut f"ur Experimentelle und Angewandte Physik, Universit"at Regensburg, 93040 Regensburg

Ballistic electron transport through GMR-structures into a semiconductor have already shown large magnetocurrent effects [1]. In our work we aim to get information about different transport processes involved.

We examine layered systems like GaAs/CoFe/Cu/NiFe/Al₂O₃/Al. The CoFe Schottky contact is epitaxially grown on n+ doped GaAs(001). The total thickness of the CoFe/Cu/NiFe pseudo spinvalve is about 10nm to allow ballistic transport. Magnetron sputtering and natural oxidation of 0.7nm Al (three repetitions) is used for the tunneling barrier.

Optical lithography is used to structure and contact the samples. With SIMS-controlled ion beam etching we are able to stop etching in the GMR trilayer. The different contacts on each sample are isolated by SiO₂, using PECVD. Contact pads of about 250nm Au finally deposited on top allow to bond the samples for electrical measurements.

For magnetic characterisation we use MOKE and SQUID magnetometers. Through I-V-measurements at different fields, temperatures and electron energies we obtain barrier and magnetotransport parameters.

[1] R. Jansen et. al., JAP 89 (2001) 7431