Regensburg 2010 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 6: TR: Nanoelectronics II: Spintronics and Magnetotransport
TT 6.7: Vortrag
Montag, 22. März 2010, 15:30–15:45, H19
Magneto-resistance of atomic-sized contacts of magnetic metals — •Stefan Egle1, Hans-Fridtjof Pernau1, Cécile Bacca1, Magdalena Huefner2, and Elke Scheer1 — 1Department of Physics, University of Konstanz, Germany — 2Solid State Physics Laboratory, ETH Zurich, Switzerland
In this talk, a comprehensive study of the magneto resistance (MR) behavior of atomic-size contacts is given, where two macroscopic electrodes are connected to a central nanobridge. An atomic contact can be adjusted by means of mechanically controllable break junction (MCBJ) technique. In order to separate the influence of the electrodes from the effect of the nanobridge itself, we employ different material systems. Namely, ferromagnetic cobalt electrodes are connected to a non-magnetic gold bridge and vice versa. The shape of the electrodes can be chosen symmetric or asymmetric and the nanobridge region can be suspended or non-suspended. Furthermore, we investigate the MR for different orientations of the magnetic field. The curves show a very rich behavior with magneto resistance ratios (MRR) up to 100% and more in the atomic contact regime, reaching up to a few 1000% in the tunneling regime. For all geometries used, the MRR values are of comparable size. Moreover, we study the possible influence of the micromagnetic order of the domains in the vicinity of the contact region as well as ballistic MR, GMR, TMR, atomically enhanced anisotropic MR (AAMR) and magnetostriction. We conclude that the AAMR is the most important contribution of the MR at large magnetic fields, while magnetostriction, TMR and GMR govern the low-field regime.