Dresden 2009 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 35: Postersession Transport: Nanoelectronics, Quantum Coherence and Quantum Information, Fluctuations and Noise
TT 35.19: Poster
Mittwoch, 25. März 2009, 14:00–18:00, P1A
Magneto-resistance of atomic-sized contacts of magnetic metals — •Stefan Egle1, Hans-Fridtjof Pernau1, Cécile Bacca1, Magdalena Hüfner2, and Elke Scheer1 — 1University of Konstanz, Germany — 2ETH Zürich, Switzerland
We report electronic transport measurements carried out on atomic-size contacts made of ferromagnetic metals or noble metals with ferromagnetic electrodes. The magneto-resistance (MR) curves show very rich behavior with strong magneto-resistance ratios (MRR) up to 1,000 %. We study the possible influence due to the micro-magnetic order of the domains in the vicinity of the contact, giant MR, tunnel MR, ballistic MR and magneto-striction by analyzing MR curves in different orientations of the applied magnetic field with respect to the film plane and current direction. In order to separate the influence of the large electrodes from the influence of the contacts themselves, we used different sample geometries. We used cobalt samples within a symmetric and an asymmetric layout as well as combinations of nonmagnetic electrodes with magnetic bridges and vice versa. In all geometries the MRR is of comparable size and the MR traces show a rich behavior. The main conclusion which we draw from our results is that the micro-magnetism of the electrodes as well as the precise atomic arrangement of the contact account for the large MR values.