Hamburg 2001 – wissenschaftliches Programm

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AM: Magnetismus

AM 10: Dünne Schichten I

AM 10.1: Vortrag

Mittwoch, 28. März 2001, 14:00–14:15, S 5.2

Growth and magnetic interaction of FeMn alloys and Co films on Cu(001) — •F. Offi, W. Kuch, and J. Kirschner — Max-Planck-Institut für Mikrostrukturpyhsik, Weinberg 2, 06120 Halle

The magnetic properties of a Co film coupled to an FeMn film were investigated using a Cu(001) single crystal as substrate. Mn, Fe, and Co were evaporated at room temperature by electron bombardment of high purity rods. The Fe_xMn_1−x alloy was obtained by co-evaporation of the two materials. Medium energy electron diffraction intensity oscillations, observed during the growth of FeMn alloys on Cu(001) and on Co/Cu(001), indicating a layer-by-laye growth mode, were used for thickness calibration. The FeMn alloy composition and thickness were checked using Auger electron spectroscopy. Magnetization curves, obtained by in-situ magneto optical Kerr effect in the longitudinal geometry, were recorded for increasing Fe₅₀Mn₅₀ thickness (t_FeMn) on top of 6 monolayers (ML) Co/Cu(001). When t_FeMn overcomes approximately 10 ML the coercive field (H_c) raises up steeply, by nearly a factor of 20. A similar situation is also encountered when Co is grown on top of Fe₅₀Mn₅₀. This abrupt change in H_c is probably related to the antiferromagnetic state of the FeMn film, when t_FeMn is such that the transition temperature (T_tr) of the antiferromagnetic phase crosses room temperature. Measurements for different thickness and Fe concentration show that T_tr is higher for higher Fe_xMn_1−x thickness and becomes smaller when x decreases.