Berlin 2005 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 16: Poster Ia

HL 16.10: Poster

Freitag, 4. März 2005, 16:30–19:00, Poster TU E

Tunneling Through Single-Crystal GaAs(001) Barriers With Sputtered Fe-Contacts — •Jürgen Moser, Marcus Zenger, Peifeng Chen, Werner Wegscheider, and Dieter Weiss — Institut für Experimentelle und Angewandte Physik, Universität Regensburg, D-93040 Regensburg

We investigate transport through epitaxial GaAs(001) barriers sandwiched between sputtered Fe-films. To realize a Fe/GaAs(001)/Fe sandwich we use the epoxy-bond-and-stop-etch-technique. To achieve different magnetic switching fields of the two sputtered Fe-layers at room temperature one of the Fe-layers is covered with Co. This layer acts as a pinning layer and leads to a high coercive field of one Fe-layer. Previous experiments have shown that tunneling is the dominant transport mechanism for these samples. A pretreatment of one GaAs surface with hydrogen plasma at RT and a small acceleration voltage to reduce the native oxide layer increases the TMR-Effect from 1.2 % to about 3 % at 4.2 K which corresponds to a spin-polarisation of about 12 % in the Jullière model. Temperature dependent measurements show a reduction of the TMR-Effect to about 0.3 % at 300 K. This reduction is much higher than expected by the temperature dependence of the magnetisation of iron.