Radial, Planar and Helical Anisotropies Induced in Cylindrical Amorphous CoP Multilayers
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STRACT Electrolytic cylindrical amorphous CoP multilayers, grown on copper wires, with controlled continuos variation of the magnetic anisotropy, in both, direction and magnitude, have been produced. The inner zone of the samples has been grown to exhibit radial anisotropy and the overlayer has been obtained with planar longitudinal anisotropy. Our studies have revealed that the magnetization at the surface of the samples is strongly coupled with the bulk anisotropy for thickness of the overlayer of z 1.5 pm. Furthermore, it has been found that an angular deformation applied to the samples, when the copper wire is subjected to a torsion, modifies the direction of the longitudinal anisotropy to the helical direction. Also, a large spontaneous Matteucci effect is induced by means of this angular deformation. INTRODUCTION There are extensive efforts to control the magnetic properties of samples appropriated as active elements in different kind of microelectronics devices: e.i control of the surfaces anisotropies', modification of the giant magnetoresistance2 Investigations in this area are being performed in the last years. The electrolytic technique 3 is process to fabricate, in a not expensive way, samples to be used as nuclei of these devices. In the present work, we show a study of the magnetic anisotropy in electrolytic cylindrical amorphous CoP multilayers, obtained varying the magnitude and the direction of the magnetic anisotropy: radial, planar or helical. The objective to produce these kind of samples was to obtain, in the same sample, two distinguished zones with different easy axis for the magnetization: the underlayer, with radial anisotropy and the overlayer, with in plane anisotropy, and study the magnetization processes monitored as a function of the multilayer thickness. Similar samples were obtained by us in a previous work, but the substrates were copper films 4. The possibility to control the magnetization processes and the anisotropy in these samples, make them suitable for many applications in microelectronics devices. Principally we have focus our studies in investigations on the evolution of the magnetic anisotropy direction of these samples and the Matteucci effect, this is, the appearance of a component of the magnetization in the circular direction in a magnetostrictive sample when it is subjected to a torsion and simultaneously a longitudinal magnetic field is applied. Some authors have reported results about spontaneous Matteucci effect 5 and helical induced anisotropies on amorphous wires 6. We have also studied this effect in a previous work 7.
489 Mat. Res. Soc. Symp. Proc. Vol. 459 01997 Materials Research Society
EXPERIMENTAL Amorphous CoP cylindrical samples were obtained by electrodeposition technique. The electrolyte was prepared according to reference 3. During the electrolytic process, its temperature was maintained at 83 'C. A Co foil was used as anode and the substrate was a copper wire, rotating around its cylindrical symmetry axis during the deposition. We report here result
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