@article{e738bb6593044256b15992f226386dc6,
title = "A multistep ac electrodeposition method to prepare Co nanowires with high coercivity",
abstract = "It is known that the ac electrodeposition method with low current density can grow compact metal nanowires, but the length of those nanowires is very short. In contrast, the ac electrodeposition method with high current density can grow long metal nanowires. However these long nanowires are not compact and contain lots of defects. In this paper, we describe a multistep ac electrodeposition method to fabricate long metal nanowires with compact structure uniformly filled upon a porous anodic aluminum oxide template. Using this method, Co nanowires with high coercivity (Hc) and remnant ratio (Mr / Ms) have been prepared under relatively low deposition current density. The Co nanowires exhibited obvious magnetic anisotropy with the easy axis along the axial direction of nanowires. The maximal Hc (2900 Oe) and Mr / Ms (0.95) were optimal for the perpendicular magnetic recording materials. The magnetic microstructure of Co nanowires is also discussed in this paper.",
author = "Pangpang Wang and Lumei Gao and Zhiyong Qiu and Xiaoping Song and Liqun Wang and Sen Yang and Murakami, {Ri Ichi}",
note = "Funding Information: This work is financially supported by the National Natural Science Foundation of China (Grant No. 50501018) and the Chinese University Doctoral Foundation of the State Education Ministry. The authors are grateful to Dr. Jian Chen for TEM measurements, Dr. Wen Guan for VSM measurements, and Dr. Yu Wang and Dr. Pankaj M. Koinkar for helpful discussion. The authors would like to thank Dr. Mark Glucina for revision check of the whole paper. FIG. 1. Top view SEM image of the AAO template prepared by a two-step anodizing method under 18 V in 0.3 mol/l H 2 SO 4 aqueous solution for 2 h at 5 ° C . The average pore diameter and interpore distance are 30 and 50 nm, respectively. FIG. 2. Schematic diagram of the growth mechanisms of Co nanowires deposited into the nanoscale pores of AAO template: (a) high current density and (b) relatively low current density (Ref. 14 ). FIG. 3. Voltage-time and current density-time curves for two electrodeposition methods: (a) constant voltage ac electrodeposition and (b) multistep ac electrodeposition. FIG. 4. TEM images of Co nanowires: (a) top view of partly dissolved AAO template with Co nanowires, (b) released Co nanowires, and (c) electron diffraction patterns for single nanowire. FIG. 5. M - H loops of the Co nanowires when θ = 0 ° and θ = 90 ° (where θ is the angle between the applied magnetic field and the axial direction of the nanowires). FIG. 6. Change curves of coercivity H c and remnant ratio M r / M s of Co nanowires depending on different θ . FIG. 7. Magnetic structures for different models: (a) chain-of-spheres model: symmetric fanning mechanism, (b) chain-of-prolate-spheroids model: symmetric fanning mechanism, and (c) single prolate spheroid model (Refs. 32–34 ). ",
year = "2008",
doi = "10.1063/1.2975843",
language = "English",
volume = "104",
journal = "Journal of Applied Physics",
issn = "0021-8979",
publisher = "American Institute of Physics Publising LLC",
number = "6",
}