SQUID studies of Co-Cu heterogeneous alloy nanowires

Heterogeneous Co20Cu80 alloy nanowires were prepared by electrodeposition a nd their magnetic properties studied using SQUID magnetometry. Magnetizatio n curves show the influence of the shape anisotropy of the wires. Zero fiel d-cooled (ZFC) initial magnetic susceptibility measurements indicate a rang e of blocking temperatures which extends at least to room temperature, sugg esting the presence of some relatively large Co-rich clusters. A sharp rise in the ZFC susceptibility for the smallest diameter wires at temperatures below about 20 K suggests that in these wires there are also some extremely small clusters present. (C) 2000 Elsevier Science B.V. All rights reserved .