Magnetic properties of Ni nanowires in self-assembled arrays

Zheng, Min; Menon, Latika; Zeng, Hao; Liu, Yi; Bandyopadhyay, Supriyo; Kirby, Roger D.; Sellmyer, David J.

doi:10.1103/physrevb.62.12282

Cited by 129 publications

(96 citation statements)

References 20 publications

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“…ac electrodeposition was used due to the dielectric nature of alumina. 16 For deposition of Co, an electrolyte containing 0.1 M CoSO 4 was used, either with or without boric acid; for deposition of Fe and Ni, CoSO 4 was substituted by FeSO 4 and NiSO 4 , respectively. The center-to-center spacing ͑D͒ and the diameter of the nanowires (d w ) can be readily controlled by electrochemical parameters.…”

Section: Methodsmentioning

confidence: 99%

Structure and magnetic properties of ferromagnetic nanowires in self-assembled arrays

et al. 2002

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Static and dynamic aspects of the magnetization reversal in nanowire arrays are investigated. The arrays have been produced by electrodeposition of ferromagnetic metals ͑Fe, Co, and Ni͒ into porous anodic alumina templates, with diameters as small as 5 nm. The crystal structures of the nanowires are bcc ͑Fe͒ and fcc ͑Ni͒ and a mixture of fcc and hcp ͑Co͒, with grain sizes of a few nanometers. Magnetic properties as a function of temperature are investigated. The temperature dependence of coercivity can be understood in terms of thermal activation over an energy barrier with a 3 2 -power dependence on the field. Coercivity as a function of diameter reveals a change of the magnetization reversal mechanism from localized quasicoherent nucleation for small diameters to a localized curlinglike nucleation as the diameter exceeds a critical value determined by the exchange length. The quasicoherent limit is described by a model that yields explicitly real-structure-dependent expressions for coercivity, localization length, and activation volume.

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Section: Methodsmentioning

confidence: 99%

Structure and magnetic properties of ferromagnetic nanowires in self-assembled arrays

et al. 2002

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“…Previously, alumina membranes obtained from the anodization of thick ͑Ͼ100 m͒ aluminum foils were mostly used for the fabrication of nanowires. [23][24][25][26][27][28][29][30] These nanowires were grown by electrodeposition, which cannot be easily adapted for the fabrication of nanodots with controlled and uniform thickness. Moreover, this method requires transfer of the alumina membranes onto a substrate.…”

Section: Introductionmentioning

confidence: 99%

Fabrication and structural characterization of highly ordered sub-100-nm planar magnetic nanodot arrays over 1cm2 coverage area

Roshchin

Batlle

et al. 2006

Journal of Applied Physics

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Porous alumina masks are fabricated by anodization of aluminum films grown on both semiconducting and insulating substrates. For these self-assembled alumina masks, pore diameters and periodicities within the ranges of 10-130 and 20-200 nm, respectively, can be controlled by varying anodization conditions. 20 nm periodicities correspond to pore densities in excess of 10 12 per square inch, close to the holy grail of media with 1 Tbit/ in. 2 density. With these alumina masks, ordered sub-100-nm planar ferromagnetic nanodot arrays covering over 1 cm 2 were fabricated by electron beam evaporation and subsequent mask lift-off. Moreover, exchange-biased bilayer nanodots were fabricated using argon-ion milling. The average dot diameter and periodicity are tuned between 25 and 130 nm and between 45 and 200 nm, respectively. Quantitative analyses of scanning electron microscopy ͑SEM͒ images of pore and dot arrays show a high degree of hexagonal ordering and narrow size distributions. The dot periodicity obtained from grazing incidence small angle neutron scattering on nanodot arrays covering ϳ2.5 cm 2 is in good agreement with SEM image characterization. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2356606͔ INTRODUCTIONNanostructured magnets have attracted great attention recently due to their unique magnetic properties which are completely different from those of continuous films and bulk materials. [1][2][3][4] In addition, nanoscale studies may shed light on the heavily investigated mechanism of exchange bias 5-9 existing in ferromagnet ͑FM͒-antiferromagnet ͑AF͒ bilayers. Fabrication of sub-100-nm FM single layer and FM/AF bilayer nanostructures offers a great opportunity for research on fundamental magnetism at the nanoscale.A variety of methods are used for nanofabrication, including electron beam and optical lithography. The low throughput and high cost of electron beam lithography lead to limited applicability for the fabrication of nanopatterns with large coverage area. Although optical lithography has high throughput, the smallest size of features that can be produced is limited by the long optical wavelength. Among many nanofabrication methods, 10-15 a promising technique is based on masks with sub-100-nm self-assembled pores. Such masks, for example, can be fabricated by the anodization of aluminum under appropriate experimental conditions. [16][17][18][19][20][21][22] Arrays of nanopores with tunable pore diameter covering more than 1 cm 2 demonstrate the potential application of porous alumina ͑AlO x ͒ masks for nanostructure fabrication. Previously, alumina membranes obtained from the anodization of thick ͑Ͼ100 m͒ aluminum foils were mostly used for the fabrication of nanowires. [23][24][25][26][27][28][29][30] These nanowires were grown by electrodeposition, which cannot be easily adapted for the fabrication of nanodots with controlled and uniform thickness. Moreover, this method requires transfer of the alumina membranes onto a substrate. Insufficient adhesion between the membrane and substrate,...

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“…A variety of nanostructures can be formed from nanodots 15,16 to nanotubes [17][18][19] with cylindrical nanowires most commonly prepared. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] In many studies, the as-deposited templated arrays of nanowires have been investigated, and this has produced significant insight into the physical behaviour of these nanowires. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] More recently, isolated individual nanowires have been studied, and these studies present the opportunity to investigate the intrinsic behaviour of individual nanowires.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14] In many studies, the as-deposited templated arrays of nanowires have been investigated, and this has produced significant insight into the physical behaviour of these nanowires. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] More recently, isolated individual nanowires have been studied, and these studies present the opportunity to investigate the intrinsic behaviour of individual nanowires. [20][21][22][23][24] Isolated nanowires are obtained by releasing the nanowires from the templates using a suitable chemical solution to dissolve the template without damaging the nanostructures.…”

Section: Introductionmentioning

confidence: 99%

Magnetic field alignment of template released ferromagnetic nanowires

Sultan

Das

Mandal

et al. 2012

Journal of Applied Physics

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A detailed investigation of magnetic field alignment of template released ferromagnetic nanowires has been undertaken. The distributions of magnetic field induced angular alignments of Ni0.8Fe0.2, Co, and Ni nanowires grown by electro-deposition and deposited onto substrates from a dilute suspension have been investigated as a function of magnetic field strengths up to ∼1 kOe. The nominal diameter of the nanowires investigated is either ∼200 nm (Ni0.8Fe0.2) or ∼300 nm (Co and Ni). The percentage of nanowires aligned within 0°–10° and 0°–20° of the applied field axis is observed to increase rapidly with increasing field strength up to ∼200 Oe, followed by a slower increase in alignment for the Ni0.8Fe0.2 and Ni wires and little improvement in alignment for the Co wires at higher fields. The proportion of aligned wires within 0°–20° is found to reach ∼82% for Ni0.8Fe0.2, ∼71% for Ni and only 53% for the Co nanowires using a magnetic field of 1 kOe. The influence of wire length upon the efficacy of magnetic alignment is investigated using Ni0.8Fe0.2 and Ni nanowires; this showed that the fractional alignment improved for longer nanowires.

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Magnetic properties of Ni nanowires in self-assembled arrays

Cited by 129 publications

References 20 publications

Structure and magnetic properties of ferromagnetic nanowires in self-assembled arrays

Structure and magnetic properties of ferromagnetic nanowires in self-assembled arrays

Fabrication and structural characterization of highly ordered sub-100-nm planar magnetic nanodot arrays over 1cm2 coverage area

Magnetic field alignment of template released ferromagnetic nanowires

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