Tuning the magnetic properties of multisegmented Ni Cu electrodeposited nanowires with controllable Ni lengths

• Published in: Nanotechnology 2016-08, Vol.27 (33), p.335301-335301
• Main Authors: Susano, M, Proenca, M P, Moraes, S, Sousa, C T, Araújo, J P
• Format: Article
• Language: English
• Subjects: Curie temperature; electrodeposition; finite-size scaling relation; nanoporous alumina templates; segmented nanowires; shape anisotropy
• ISSN: 0957-4484; 1361-6528
• DOI: 10.1088/0957-4484/27/33/335301

The fabrication of segmented Ni Cu nanowires (NWs), with tunable structural and magnetic properties, is reported. A potentiostatic electrodeposition method with a single electrolytic bath has been used to fabricate multisegmented Ni Cu NWs inside a highly hexagonally ordered anodic nanoporous alumina membrane, with diameters of 50 nm and Ni segment lengths (LNi) tuned from 10 nm up to 140 nm. The x-ray diffraction results evidenced a strong dependence of the Ni NWs crystallographic face-centered-cubic (fcc) texture along the [220] direction on the aspect ratio of the NWs. The magnetic behavior of the multisegmented Ni Cu NW arrays, as a function of the magnetic field and temperature, is also studied and correlated with their structural and morphological properties. Micromagnetic simulations, together with the experimental results, showed a dominant antiferromagnetic coupling between Ni segments along the wire length for small low aspect-ratio magnetic segments. When increasing the Ni segments' length, the magnetic interactions between these along the wire became stronger, favouring a ferromagnetic coupling. The Curie temperature of the NWs was also found to strongly depend on the Ni magnetic segment length. Particularly the Curie temperature was found to be reduced 75 K for the 20 nm Ni segments, following the finite-size scaling relation with 0 = 8.1 Å and γ = 0.48. These results emphasize the advantages of using a template assisted method to electrodeposit multilayer NWs, as it allows an easy tailor of the respective morphological, chemical, structural and magnetic properties.