By ab initio LMTO calculations in the atomic sphere approximation we study the oscillatory thickness dependence of the exchange coupling between ferromagnetic CO slabs grown epitaxially on the (001) surface of a f.c.c. Cu spacer in a d,-Co/&-Cu multilayer structure and find not only the well-known oscillations with the spacer thickness 4 , but-as a new result-also a pronounced oscillation with the magnetic thickness dl . Thus, the experimentalist should not only vary, as usual, the spacer thickness 4 , but also the magnetic thickness dl , when trying to optimize the exchange coupling of the system for applications.

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We perform first-principles calculations for the three multilayer systems (100)-Co 1 /Cu n , NiCo 2 Ni/Cu n and Co 4 Cu n , and find from a comparison of the results for system 2 and 3 that amplitude and phase of the exchange coupling are sensitive to the magnetic-slab/nonmagneticspacer interface. Moreover, we observe that for the system 1 the averaged magnetic moment of the magnetic slab oscillates with the spacer thickness similarly as the exchange coupling.

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By means of self-consistent semi-empirical LCAO calculations we study the itinerant magnetism of (Fe 0.65 Ni 0.35 ) 1−y Mn y alloys for y between 0 and 0.22 at T = 0 K, neglecting only the transverse spin components. We find that the magnetic behaviour is quite complicated on a local scale. In addition to ferromagnetic behaviour, also metastable spin-glass-like configurations are found. In the same approach, using a direct numerical calculation by the Kubo-Formalism without any fit parameters, we also calculate the electrical conductance in the magnetic state and find that the y-dependence observed in the experiments is well reproduced by our calculations, except of an overall factor of ≈ 5, by which our resistivities are too large. * based on the Diploma thesis of A. Paintner, Regensburg 1994