Controlled changes in the microstructure and magnetic anisotropy in arrays of electrodeposited Co nanowires induced by the solution pH

Darques, M.; Encinas, Armando; Vila, Laurent; Piraux, Luc

doi:10.1088/0022-3727/37/10/001

Cited by 123 publications

(108 citation statements)

References 24 publications

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“…Contrary to squarelike hysteresis loops of isolated (i.e., noninteracting) Co NWs [22] the parallel hysteresis loops are significantly sheared, hinting further on the presence of strong magnetostatic interactions between NWs. Even though the sample with the thickest wires (d = 90 nm) behaves similar to bulklike ferromagnetic thin films, the out-of-plane (in-plane) coercivity still remains large (small).…”

Section: Resultsmentioning

confidence: 91%

Diameter‐Controllable Magnetic Properties of Co Nanowire Arrays by Pulsed Electrodeposition

Yang

Chen

et al. 2010

Journal of Nanomaterials

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The Co nanowires with different diameters were prepared by pulsed electrodeposition into anodic alumina membranes oxide templates. The micrographs and crystal structures of nanowires were studied by FE-SEM, TEM, and XRD. Due to their cylindrical shape, the nanowires exhibit perpendicular anisotropy. The coercivity and loop squareness (Mr/Ms) of Co nanowires depend strongly on the diameter. Both coercivity and Mr/Ms decrease with increasing wire diameter. The behavior of the nanowires is explained briefly in terms of localized magnetization reversal.

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Section: Resultsmentioning

confidence: 91%

Diameter‐Controllable Magnetic Properties of Co Nanowire Arrays by Pulsed Electrodeposition

Yang

Chen

et al. 2010

Journal of Nanomaterials

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“…As the length of Co nanowires increases, hcp-phase peaks are observed and become almost the only detected for the longest (1000 nm long) nanowires. The intensity of the hcp-(100) peak at 2u ¼ 41.78 denotes a textured structure, which has been ascribed to perpendicular crystalline anisotropy [17,39]. Less intense hcp-(002) and hcp-(101) peaks appear at 2u ¼ 44.5 and 47.48, respectively, which have been correlated with longitudinal and at 458 magnetocrystalline anisotropy.…”

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confidence: 99%

Magnetization reversal in Co‐base nanowire arrays

Vázquez

Vivas

2011

Physica Status Solidi (b)

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The magnetic behaviour of ordered arrays of magnetic nanowires is controlled by the combined action of anisotropy energy terms determined by geometrical shape, crystalline structure and magnetostriction, as well as by the magnetostatic interactions among them. A number of works have been reported on the role of magnetostatic interaction in arrays of nanowires, sometimes focusing on nanowires with vanishing crystalline and magnetostrictive energy terms. Here, in turn we are interested in Co‐base nanowires whose magnetocrystalline anisotropy plays a very important role. Arrays of Co‐base nanowires offer novel, sometimes unexpected behaviour that is not fully understood. Such results are connected to their magnetocrystalline anisotropy, and to their complex magnetization reversal mode. Arrays of Co and Co‐base nanowires have been fabricated by template‐assisted method, by electroplating into highly ordered self‐assembled pores of nanoporous alumina membranes. Their hcp or fcc crystal structure is confirmed to depend on length of nanowires as well as on the presence of selected elements in the composition. The magnetic behaviour of these arrays has been experimentally investigated as a function of (i) geometry (e.g. diameter and, particularly short length) and (ii) composition (e.g. adding Ni or Pd). A complementary study on its temperature dependence reveals the nature of the dominant anisotropy, while the angular dependence of hysteresis loops (e.g. coercivity and remanence) enables a deeper analysis of the magnetization reversal process. Micromagnetic reversal modes are reviewed and modelling and simulations procedures introduced. Complex rotational mechanisms are concluded to be responsible for the reversal process following micromagnetic modes distinct from those pure classically established. SEM image of an array of Co‐base nanowires.

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“…By contrast, Henry et al 19 report that in small diameter ͑Ͻ50 nm͒ wires an alignment of the c axis with the wire axis is preferred. Very recently, Darques et al 20,21 have suggested that the orientation of the c axis can be controlled by adjustment of the electroplating solution and the deposition conditions. In our nanowire arrays the simultaneous presence of ͑100͒, ͑002͒, and ͑110͒ reflections precludes a single orientation of c axis either parallel or normal to the wire axis.…”

Section: Discussionmentioning

confidence: 99%

Co-rich cobalt platinum nanowire arrays: Effects of annealing

Peng

Jones

et al. 2005

Journal of Applied Physics

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The effects of annealing on the crystal structure and magnetic properties of Co-rich cobalt platinum nanowire arrays embedded in anodic aluminium oxide membranes have been investigated. For this purpose, a rapid thermal annealing to temperatures of 300°C to 800°C has been used. Transmission electron microscopy and scanning electron microscopy show that the nanowires have a mean diameter of 14 nm and an estimated wire density of 7.8ϫ 10 10 cm −2 . From x-ray diffraction patterns, we find that the nanowires are hcp and possess a preferred texture in which the c axis of the grains tends to lie along the major axis of the wire. Vibrating sample magnetometry measurements indicate that the easy axis is along the nanowire axis direction. Hysteresis loops, saturation magnetization, squareness ratio ͑M r / M s ͒, and coercivity ͑perpendicular and parallel to the nanowire axis͒ have all been investigated as a function of the annealing temperature ͑T A ͒. Coercivity parallel to the wire axis first increases with T A , attains a maximum at 600°C ͑which is 150% of the as-deposited sample͒, and then decreases. By contrast there is relatively little change in the coercivity measured perpendicular to the wires. The saturation magnetization for the as-deposited sample is 1360 emu/ cc and remains almost constant for annealing temperatures up to 500°C: for T A Ͼ 500°C it decreases significantly. The maximum ͑M r / M s ͒ ratio attained in this study is 0.99, the highest value reported thus far for cobalt platinum alloy nanowires. The data suggest that these materials are potential candidates for high-density magnetic recording media.

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Controlled changes in the microstructure and magnetic anisotropy in arrays of electrodeposited Co nanowires induced by the solution pH

Cited by 123 publications

References 24 publications

Diameter‐Controllable Magnetic Properties of Co Nanowire Arrays by Pulsed Electrodeposition

Diameter‐Controllable Magnetic Properties of Co Nanowire Arrays by Pulsed Electrodeposition

Magnetization reversal in Co‐base nanowire arrays

Co-rich cobalt platinum nanowire arrays: Effects of annealing

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