Template-assisted Co–Ni alloys and multisegmented nanowires with tuned magnetic anisotropy (Phys. Status Solidi A 5∕2014)




Nanostructured magnetic materials synthesized through electrochemical methods by employing nanoporous anodic aluminum oxide membranes as patterned templates have recently attracted a huge attention. In their work reported on pp. 1041–1047, García et al. synthesized Co100-xNix (15 ≤ x ≤ 61) alloy nanowires of about 180 nm in diameter and 14 μm in length, as well as multisegmented Co54Ni46/Co85Ni15 nanowires with an approximate length of 300 nm per each segment, by means of electrochemical deposition into the pores of hard-anodic alumina membranes. The composition and crystalline structure of Co-Ni alloy segments and nanowires were properly adjusted by varying the electrodeposition potential. The magnetic properties of the alloyed nanowire arrays were correlated with their microstructural features. Co-richer nanowires show a hard magnetic phase due to the stronger influence of the high magnetocrystalline anisotropy of the majority hcp phase, whilst the Co-poorer ones exhibit a softer magnetic phase (fcc) and their magnetic behaviour is mainly determined by shape anisotropy. The comparison between the alloyed nanowires with different cobalt contents sheds light into the magnetization processes determining the overall magnetic behaviour of the multisegmented nanowire arrays.