PUB - Publikationen an der Universität Bielefeld

Employing different types of decomposition the dependence of giant magnetoresistance (GMR) on the interplay between spin-dependent scattering at second phase particle interfaces and their presence as isotropically or anisotropically oriented scattering sites has been studied by comparing: (1) dispersions of Co clusters embedded in Cu, (2) a lamellar eutectic consisting of alternating stacking of Co and Au-rich lamellae and (3) spinodally decomposed and aligned ferromagnetic particles in AlNiCo5 and FeCrCo. In melt-spun Cu100-xCox the Co concentration has been varied from x = 0 up to the three dimensional percolation limit for an fee lattice. A transition from anisotropic magnetoresistance (AMR) to GMR was observed for x < 2 at.%. GMR behavior dominates for x greater than or equal to 2 at.% with a maximum amplitude of 35% at 10 K and 7% at 293 It. In Au71.6Co28.4 the GMR effect is only 1.4% at 300 K and 2.8% at 10 K, but it is linked to the multilayer like eutectic microstructure. GMR amplitudes in AlNiCo5 at 16 T sizes as much as 6.5% at 10 K and 4.25% at 300 K and depend on the direction of the current with respect to the aligned ferromagnetic particles. The probability of magnetic scattering is two times more likely when the current is applied perpendicular to the direction of the particle elongation. A transition from AMR to GMR is observed for FeCrCo upon annealing. (C) 1997 Elsevier Science S.A.