Abstract

In the present work, we report the studies of temperature dependence of magnetic properties in thin microwires with composition Cu80Co19Ni1. An extensive study of structural and magnetic characterization was realized. The structure was observed using X-ray diffraction with CuK alpha radiation. The magnetic measurements were carried out using a SQUID at temperatures between 5 and 300 K. The as-prepared Cu80Co19Ni1 microwire presents a coercivity of about 80 Oe. The variation of the coercivity and remanent magnetization at 5-300 K were obtained from the hysteresis loops. From the difference of the ZFC and FC curves below T = 100 K, we can assume the presence of small superparamagnetic grains embedded in the Cu matrix. Those superparamagnetic grains should be blocked at temperatures below the maximum of the magnetization observed below 50 K. The measurements show an unusual temperature dependence of the coercive field, consequence of a coexistence of blocked and unblocked particles, and the typical decreasing behaviour of the remanence increasing temperature. (c) 2007 Published by Elsevier B.V.