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We have studied Co/Cu multilayers to understand the effect of the sample's width on their magneto-resistance (MR). By keeping constant both the length and the thickness and exploring the widths within the range of usual magnetic domain sizes in those nanostructures, we were able to observe effects on the MR curve, as well as infer linked changes in the magnetization process. Associating MR and Planar Hall Effect (PHE) measurements, coupled to an analysis of the MR plots' symmetry, we were able to establish that, apart from the expected antiferromagnetic coupling, reducing the width forces the magnetization to stay aligned to the current channel, thus inducing more symmetric, closer to model Giant Magnetoresistance (GMR). Also, the sample edges might contribute by adding extra coupling through magnetostatic interaction. The added effects result in a counter-intuitive trend that goes from the near ideal wide samples through intermediate sizes with fairly abrupt changes in MR, and finally to the closer to bell-shaped ideal GMR at narrow widths. [ABSTRACT FROM AUTHOR]

Presents a study which described the magnetic and transport properties of iron and chromium superlattices grown on gallium arsenide by molecular-beam epitaxy. Characterization of the superlattices by high-energy electron diffraction; Discussion of the magnetic behavior of the superlattices; Origin of the antiferromagnetic coupling.

In this work, a study of the stress relief in Finemet ribbons, Fe[sub 73.5]Cu[sub 1]Nb[sub 3]Si[sub 16.5]B[sub 6], as a function of the annealing temperature is presented. The as melt-spun samples are amorphous and become partially crystallized after annealing at appropriate temperatures. For temperatures T[sub A] ≥ 480 °C the samples are nanocrystalline, with a microstructure composed by α-Fe[sub 1-χ] Si[sub χ] (χ ∼ 0.2) crystallites (10 nm average diameter) embedded in an amorphous matrix. Nanocrystallization, associated with stress relief effects, improves the soft magnetic properties of this kind of material. The stress level was quantified using magnetorestriction (measured by SAMR), magnetoelastic anisotropy, and domain wall energy data obtained from impedance spectra measurements. A reduction of the internal stress from 15 to 0.2 MPa was verified when comparing the as-cast to the sample annealed at 580 °C. Improvement of the magnetic softness of the samples was also followed by the increase of the domain wall and magnetization rotation contributions to the overall effective permeability. [ABSTRACT FROM AUTHOR]