We have fabricated extremely uniform arrays of polycrystalline Fe-Co-Ni ternary alloy nanowires having composition Fe 12.3 wt.%, Co 43.9 wt.% and Ni 43.8 wt.%. The wires are made by electrodeposition into nanoporous alumina templates, using an electrodeposition voltage of 15 V at 1000 Hz. Nanowires have been fabricated having diameters ranging from 43 nm to 120 nm, and lengths of 3 microm to 7 microm, as dependent upon template topology. The magnetization easy axis lies along the nanowire length, with an easy axis coercivity of 72 kA/m. 相似文献
We have investigated the magneto-optical properties of highly ordered Co-Pt alloy nanowire arrays embedded in anodic aluminum oxide templates. The magnetic field-dependent Stokes parameters, Faraday rotation angle and ellipticity were investigated by an in-house magneto-optical measurement system. The extracted hysteresis loops are broadly consistent with magnetic hysteresis loops obtained from the vibrating sample magnetometer. The maximum Faraday rotation angle and ellipticity of these samples were examined as a function of nanowire composition. With an increase of platinum content from 9 at.% to 86 at.% in the as-deposited nanowire arrays, the maximum Faraday rotation angle per length decreases linearly from 1.39 x 10(3) degrees/cm to 1.58 x 10(2) degrees/cm. The maximum ellipticity shows a similar behavior with the composition. These linear relationships suggest a dilution model for the magnetic moment in the alloy nanowires. Our results indicate that magneto-optical measurements comprise an effective and sensitive method for monitoring the behavior of AAO-based magnetic nanowire arrays. 相似文献
Highly ordered arrays of Co1−xZnx (0 ≤ x ≤ 0.74) nanowires (NWs) with diameters of ∼35 nm and high length-to-diameter ratios (up to 150) were fabricated by co-electrodeposition of Co and Zn into pores of anodized aluminum oxide (AAO) templates. The Co and Zn contents of the NWs were adjusted by varying the ratio of Zn and Co ion concentrations in the electrolyte. The effect of the Zn content, electrodeposition conditions (frequency and pH) and annealing on the structural and magnetic properties (e.g., coercivity (Hc) and squareness (Sq)) of NW arrays were investigated using X-ray diffraction (XRD), scanning electron microscopy, electron diffraction, and alternating gradient force magnetometer (AGFM). XRD patterns reveal that an increase in the concentration of Zn ions of the electrolyte forces the hcp crystal structure of Co NWs to change into an amorphous phase, resulting in a significant reduction in Hc. It was found that the magnetic properties of NWs can be significantly improved by appropriate annealing process. The highest values for Hc (2050 Oe) and Sq (0.98) were obtained for NWs electrodeposited using 0.95/0.05 Co:Zn concentrations at 200 Hz and annealed at 575 °C. While the pH of electrolyte is found to have no significant effect on the structural and magnetic properties of the NW arrays, the electrodeposition frequency has considerable effects on the magnetic properties of the NW arrays. The changes in magnetic property of NWs are rooted in a competition between shape anisotropy and magnetocrystalline anisotropy in NWs. 相似文献
Highly hexagonally ordered CoPd alloy nanowire arrays were synthesized through electrochemical deposition techniques into the nanopores of anodic alumina membranes used as templates. Two different electrolytes were used for this purpose, one with pH = 4.1 and the other with pH = 7. Under applying different electrodeposition parameters and by adjusting both, the current density and the electrolyte composition, it could be possible make to vary the composition of CoPd alloy nanowires in a wide range. Their composition and morphology were investigated by SEM and EDX. The magnetic properties of the nanowires array have been measured with a VSM as a function of the temperature, ranging from RT down to 50 K, for different CoPd alloy nanowires composition. Also, the temperature influence on the reversible-irreversible magnetization processes related with the magnetization reversal of the CoPd nanowires array has been analyzed by first order reversal curve (FORC) method. 相似文献
A nanofabrication method for the production of ultra-dense planar metallic nanowire arrays scalable to wafer-size is presented. The method is based on an efficient template deposition process to grow diverse metallic nanowire arrays with extreme regularity in only two steps. First, III–V semiconductor substrates are irradiated by a low-energy ion beam at an elevated temperature, forming a highly ordered nanogroove pattern by a “reverse epitaxy” process due to self-assembly of surface vacancies. Second, diverse metallic nanowire arrays (Au, Fe, Ni, Co, FeAl alloy) are fabricated on these III–V templates by deposition at a glancing incidence angle. This method allows for the fabrication of metallic nanowire arrays with periodicities down to 45 nm scaled up to wafer-size fabrication. As typical noble and magnetic metals, the Au and Fe nanowire arrays produced here exhibited large anisotropic optical and magnetic properties, respectively. The excitation of localized surface plasmon resonances (LSPRs) of the Au nanowire arrays resulted in a high electric field enhancement, which was used to detect phthalocyanine (CoPc) in surface-enhanced Raman scattering (SERS). Furthermore, the Fe nanowire arrays showed a very high in-plane magnetic anisotropy of approximately 412 mT, which may be the largest in-plane magnetic anisotropy field yet reported that is solely induced via shape anisotropy within the plane of a thin film.
The optical properties of electrodeposited zinc copper telluride (ZnCuTe) ternary nanowires on ITO substrate using polycarbonate membrane (Whatman) of diameter 200,100 and 50?nm have been studied and reported in this paper. Scanning electron microscopy confirmed the formation of the standing nanowires having uniform diameter equal to the diameter of the template used. UV–vis absorption and photoluminescence (PL) spectroscopy were used for optical studies. The optical band gaps of 200, 100 and 50?nm have been calculated as 3.19, 3.39 and 3.57?eV, respectively using UV–vis spectroscopy. The UV–visible absorption spectrometry reveals the absorption spectra of 200, 100 and 50?nm shows a blue shift. UV–visible absorption depicts that the band gap increases with decrease in the diameter size of the nanowires. Several broad emission lines have been observed over a wide wavelength range (390–690?nm) of visible light spectrum in the PL spectra of ZnCuTe nanowires of diameter 200, 100 and 50?nm. A good emission peak at around 615?nm has been observed in all nanowires. 相似文献
We report the size effect on the magnetic properties in Fe(7)S(8) nanowire arrays. Samples with diameters in the range of 50-200?nm have been prepared by electrodeposition with AAO films. The M?ssbauer measurement results show that four parameters (hyperfine fields, isomer shift, quadrupole splitting, full width at half-maximum) increased with decreasing the diameter of the nanowires. The magnetic properties were investigated. The hysteresis loop shape and the magnetization are dependent on the diameter of the nanowires. The thermomagnetic measurements on the as-synthesized nanowire samples and the corresponding bulk display a mixed-type curve and a Weiss-type curve, respectively. 相似文献
Highly uniform Co/Cu multilayer nanowire arrays had been electrodeposited into the nanochannels of porous anodic aluminum oxide template. X-ray diffraction pattern showed that Co and Cu grow in their HCP and FCC structures, respectively. Each nanowire had the same length with 20 μm and the diameter with 50 nm. The thickness of Co was 50 nm and Cu layer was about 5 nm. Magnetic measurements of the nanowire arrays showed that the magnetic coercivity for the applied field parallel to the nanowires is larger than that perpendicular to the anowires. The magnetic coercivity of Co multilayer nanowire arrays is smaller than that of the Co/Cu nanowire arrays and the crystal direction of Co layers were not obviously affected by Cu layer. The Co/Cu nanowire arrays exhibited excellent Giant Magneto Resistive ratio of about 75%. 相似文献
We report on the fabrication of silicon nanostructures with a high aspect ratio that were created using a combination of electrochemical etching and alkaline etching. With this technique, we were able to fabricate nano- and/or micro-wire structures that are perfectly periodic over large areas of 3.14 cm2. After porous silicon was created by electrochemical etching, the effect of post-alkaline etching was investigated to determine how changes in the etching time, solution concentration and temperature of the etchant influenced the silicon morphology. As a result, periodic silicon wire arrays with good vertical alignment were obtained, and these arrays had a width of less than 500 nm and/or a high aspect ratio of more than 20. 相似文献
A simple and nonexpensive adapted dip-coating technique is presented and used to fabricate arrays of magnetic nanowires with a linear varying height profile. This approach allows controlling the wire height from tenths of nanometers up to several micrometers. Furthermore, the main parameters of this height gradient can be controlled, such as the maximum wire height and the lateral span of the wire array, which can be predicted with excellent accuracy using a proposed analytical model. Moreover, we show that by sequential electrodeposition with dip-coating, arrays of these height varying wires can be grown. This technique represents a novel method to fill porous templates with controlled spatial growth, leading to the fabrication of novel structures and providing control over structural features on the nanoscale level. In particular, the use of these asymmetrically loaded magnetic nanowired substrates to obtain improved microwave nonreciprocal behavior is shown for a microwave phase shifter. 相似文献
A method of fabricating horizontally-aligned zinc-oxide (ZnO) nanowire (NW) arrays with full control over the width and length is demonstrated. SEM images reveal the hexagonal structure typical of zinc oxide NWs. Arrays of high-aspect ratio horizontal ZnO NWs are fabricated by making use of the lateral overgrowth from dot patterns created by electron beam lithography (EBL). An array of patterned wires are lifted off and transferred to a flexible PDMS substrate with possible applications in several key nanotechnology areas. 相似文献
Bismuth oxychloride (BiOCl) nanowire arrays have been successfully prepared employing the Anodic Aluminum Oxide (AAO) template assisted sol-gel method. Nanowires of 100 nm diameter and length 2-6 μm, assembled in the porous of AAO templates, were formed. XRD and HRTEM results show that the nanowires are pure BiOCl polycrystal phase without Bi2O3 or BiCl3. The photocatalytic activity of BiOCl nanowire arrays was investigated by the degradation of Rhodamine B dye solution under UV irradiation. 相似文献