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AM: Magnetismus

AM 9: Poster: Magnetowid. (1-17), Dü. Schichten (18-34), Oberfl
ächenmag. (35,36), Mikr. Methoden (37-45), Mikromag. (46-58), Phasenüberg. (59-77), Spektroskop. (78-91), Nanokr.Mat.(92-96), Anisotrop. (97-101), Schmelzen(102-104),Sonst/postdeadl.(105-109)

AM 9.43: Poster

Dienstag, 27. März 2001, 14:45–19:00, Foyer S 3

Studying thin Al-O_x barriers with a scanning tunneling microscope (STM) — •S. Czerkas and G. Reiss — Universität Bielefeld

Recently, magnetic tunnel junctions have gained enormous interest due to their potential applicability as magnetic memory cells or field sensors. Such tunnel junctions consist of two ferromagnetic electrodes separated by a thin oxide barrier. The properties of this insulating barrier are crucial for a proper operation of a junction. Surprisingly there are only very few STM studies of thin insulating barriers grown on a metal. The main goal of our study was spatially resolved investigation of aluminium oxide barrier by means of the scanning tunneling (current/voltage) spectroscopy. We prepared thin oxide barriers by natural oxidation of a 1 nm thick Al film grown on 8 nm thick Co film on SiO₂ wafer. For the sake of comparison samples with only Co film were also examined. The barrier parameters i.e., their thickness and height, were obtained from the I−U curves. We were able to observe spatial variations of the barrier parameters. This phenomenon can be explained by the growth mode of the Al films and spatial inhomogenities of the oxidised Al layer.

This work has been partially supported by the German Ministry of Education and Research under grant #13N7382/6