Preparation of electrodeposited cobalt nanowires

Caffarena, Valeska da Rocha; Capitaneo, Jefferson Leixas; Simão, Renata Antoun; Guimarães, A.P.

doi:10.1590/s1516-14392006000200017

Cited by 24 publications

(8 citation statements)

References 8 publications

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“…The template-assisted electrodeposition method [14,15] has proven to be a successful technique to synthesize vertically aligned metallic nanowires. By controlling the deposition conditions and the geometry of porous anodic aluminum oxide (AAO) template, this method enables better stoichiometric composition and geometric dimension of the as-grown nanowires.…”

Section: Synthetic Approachmentioning

confidence: 99%

Shape Anisotropy and Magnetization Modulation in Hexagonal Cobalt Nanowires

Liu

Chang

et al. 2008

Adv Funct Materials

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Ferromagnetic cobalt nanowires with high‐crystalline quality are synthesized using a low‐voltage electrodeposition method. High‐resolution transmission electron microscopy (HRTEM) and X‐ray diffraction (XRD) results show that the nanowires are uniform in size, and consist of predominantly hexagonal close‐packed (hcp) structure with the magnetocrystalline easy axis (c‐axis) perpendicular to the wire axis. Superconducting quantum interference device (SQUID) measurements illustrate the dominance of shape anisotropy, manifested by the weak temperature dependence of the enhanced coercive field along the wire axis. Furthermore, the magnetic structures of individual, segmented, or intersected nanowires are studied using magnetic force microscopy. This reveals a strong dipole at the two ends of the wire, together with a spatial magnetization modulation along the wire. Based on theoretical modeling, such intrinsic modulation is attributed to magnetization frustration due to the competition between the magnetocrystalline polarization along the easy axis and the shape anisotropy along the wire axis.

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Section: Synthetic Approachmentioning

confidence: 99%

Shape Anisotropy and Magnetization Modulation in Hexagonal Cobalt Nanowires

Liu

Chang

et al. 2008

Adv Funct Materials

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“…These results were again contrasting, where some researchers observed ferromagnetic ordering at lower doping concentration but paramagnetic behavior for higher doping concentration. For iron doping, it was explained that paramagnetic behavior is due to antiferromagnetic coupling at higher doping concentration [11,[18][19][20]. In our cobalt-doped samples, a cobalt proportional ferromagnetic strength was observed due to different electronic configurations of cobalt and agglomeration of a little fraction of cobalt atoms (as revealed by XRD) which prevents anti-ferromagnetic coupling.…”

Section: Xrd Graphs Of Doped Zno Nano-particles (Shown Inmentioning

confidence: 60%

“…Although these peaks are very feeble, they exist and represent agglomeration of cobalt atoms at higher doping ratios. Distortion or other type of degradation (like shift of peaks and decrease of crystallinity) was not observed in doped samples as claimed by researchers working with Fe and Mn as dopants [11,12]. The crystallite size calculated using Scherer's formula was found to be 14.61, 14.9, and 15.27nm for 1%, 3%, and5% (impurity vs. crystallite size graphically shown in Figure 2) cobalt-doped ZnO, respectively.…”

Section: Methodsmentioning

confidence: 71%

Effect of doping concentration on absorbance, structural, and magnetic properties of cobalt-doped ZnO nano-crystallites

et al. 2012

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Controlled conduction of magnetic spins is desired for data processing in modern spintronic devices. Transition metal-doped ZnO is a potential candidate for this purpose. We studied the effects of cobalt doping on structural, absorbance, and magnetic properties of ZnO nano-particles. Different compositions (Zn 0.99 Co 0.1 O, Zn 0.97 Co 0.3 O, and Zn 0.95 Co 0.5 O) of cobalt-doped ZnO were fabricated using metallic chlorides by co-precipitation method. XRD revealed standard ZnO wurtzite crystal structure without lattice distortion due to impurities but showed presence of additional phases at higher doping ratios. Fourier transformed infrared spectroscopy also confirmed the standard ZnO profiles at lower doping ratios but additional phases at higher doping. Vibrating sample magnetometer showed soft ferromagnetic behavior for low impurity samples and harder ferromagnetic behavior for higher doping at room temperature. A simultaneous differential scanning calorimetry/thermo gravimetric analysis was performed to study the phase variations during crystallization.

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“…Thus, results can be affected by some noise but still following the trends discussed below. In practical terms we consider here the following dimensions for the wires: 2 = 12000 nm, = 700 nm, and = 260 nm which are realistic geometrical characteristics taken from the literature [1,2,5,14]. In addition we assume a dominant shape anisotropy so the magnetization is along the cylindrical axis in any of the two directions.…”

Section: System and Methodologymentioning

confidence: 99%

“…However, this technology has at least two disadvantages for some specific uses: they are visible to anybody so they could be replicated (a single photocopy is enough) and they can get easily damaged by peeling or scratching. We propose here to store the same information in the form of magnetic bar codes stored by arrays of magnetic nanowires trapped in the porous membrane used to produce them [1][2][3][4][5][6]. Such information is now hidden (not easily replicated) and friction on them would not hamper the information.…”

Section: Introductionmentioning

confidence: 99%

Stability of Bar Code Information Stored in Magnetic Nanowire Arrays

Cisternas

Vogel

Faundez

2017

Advances in Condensed Matter Physics

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Firmware applications such as security codes, magnetic keys, and similar products can be stored in magnetic bar codes similar to optical bar codes. This can be achieved on the triangular lattice present in porous alumina, whose pori can be filled by magnetic material, over which magnetic bar codes can be inscribed. We study the conditions to improve the durability of the stored information by minimizing the repulsive energy among wires with parallel magnetization within the same bar but interacting with attractive energy with wires in the neighboring bar. The following parameters are varied to minimize the energy of the system: relative amount of magnetization orientation within the bar code area in any orientation, width of the bars, and distribution of wider bars to the outside or to the inside of the code. It is found that durability of the code is favored for equal amount of magnetization in each direction, abundance of narrow bars trying to locate a few wider ones towards the center. Three real commercial optical bar codes taken at random were mapped into magnetic bar codes; it is found that the corresponding magnetic energies are similar to those analyzed here which provides a realistic test for this approach.

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Preparation of electrodeposited cobalt nanowires

Cited by 24 publications

References 8 publications

Shape Anisotropy and Magnetization Modulation in Hexagonal Cobalt Nanowires

Shape Anisotropy and Magnetization Modulation in Hexagonal Cobalt Nanowires

Effect of doping concentration on absorbance, structural, and magnetic properties of cobalt-doped ZnO nano-crystallites

Stability of Bar Code Information Stored in Magnetic Nanowire Arrays

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