Regensburg 2007 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 18: Spindependent Transport II
MA 18.8: Vortrag
Mittwoch, 28. März 2007, 17:00–17:15, H22
Temperature dependent two-phase behaviour of magnetisation and spin polarisation in NiPt — •Markus Schäfers, Andy Thomas, and Günter Reiss — Bielefeld University, Universitätsstraße 25, D-33615 Bielefeld, Germany
We investigated the temperature dependent behaviour of magnetisation and spin polarisation in NiCu and NiPt alloys. The advantage of these alloys is the reduced Curie temperature compared with pure Nickel. The whole range of magnetisation is accessible in experiment for these alloys.
Magnetic tunnel junctions with these alloys as free electrode were prepared by dc-magnetron sputtering in an UHV system with a base pressure of 1·10−7 mbar and argon ion beam etching. TMR ratio was measured temperature dependent with a dc 2-point method. Spin polarisation was calculated by Julliere’s formula. Magnetisation was measured with a SQUID for different temperatures.
The NiPt alloy showed a maximum for in-plane magnetisation and spin polarisation at about 190 K. There are indications for a perpendicular magnetic anisotropy at low temperatures in the NiPt alloy.