Ribbons and micro-wires of CuCo segregated alloys

Abstract We have studied the TEM image contrasts present in micro-wires of CuCo metastable alloys embedded in glass, produced by the Taylor-Ulitovsky method. The results show that, despite a large stress induced by the glass covering, a nanostructure typical of spinodal decomposition appears. This is in all similar to the quasi-periodic stripe patterns seen in bulk CuCo ribbons made by melt-spinning we have observed previously. Also, the period seen in the micro-wires is smaller than that of the ribbons. The giant magnetoresistance (GMR) for these micro-wires is smaller than that of the ribbons, which agrees with the observation that a smaller GMR is seen when there appears an extra smaller period decomposition upon annealing. The superparamagnetic behavior is rather similar to that of the ribbons, but we are amiss of a reasonable explanation linking the lamellar nanostructure to its magnetism.