Arrays of nanoscale magnetic dots: Fabrication by x-ray interference lithography and characterization

Heyderman, Laura J.; Solak, Harun H.; Dávid, Christian; Atkinson, D.; Cowburn, R. P.; Nolting, F.

doi:10.1063/1.1821649

Cited by 91 publications

(47 citation statements)

References 19 publications

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“…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][11][12][13][14][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.…”

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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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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“…With nonlinear spatial frequency multiplication techniques, this limit can be reduced by factors of 1/2, 1/3, etc.-extending well into the nanoscale regime. Soft X-ray IL using synchrotron radiation has been performed as well [188][189][190]. The theoretical limit was about 3 nm.…”

Section: Other Methodologiesmentioning

confidence: 99%

3D THz metamaterials from micro/nanomanufacturing

Moser

Rockstuhl

2011

Laser & Photonics Reviews

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Metamaterials are engineered composite materials offering unprecedented control of wave propagation. Despite their complexity, effective properties can frequently be extracted by conceptualizing them as homogeneous and isotropic media with dispersive electric permittivity and magnetic permeability. For an ideal isotropic medium, strong dispersion in these properties causes wave and field vectors to form a left-handed (E,H,k)-frame involving backward waves, and offering control of quantities like the refractive index which may become negative. Experimental evidence exists from microwaves to the visible. Applications include sub-wavelength-resolution imaging, invisibility cloaking, plasmonics-based lasers, metananocircuits, and omnidirectional absorbers. As the engineered sub-structures must be smaller than their design wavelength, micro/nanomanufacturing is exploited from primary pattern generation over lithography to templating and molecular beam epitaxy. 3D metamaterials have been made by stacking of layers, multilayer structuring, and 3D primary pattern generation. Theory shows that full properties may build up over one or a very few layers.

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“…The technology of fabrication of MDAs [10,11,12,13] has been perfected to an excellent degree in the past few years. In practice, however, an occurrence of technological defects and local irregularities has still a great influence on all of the magnetic properties [14].…”

Section: Introductionmentioning

confidence: 99%

The dynamical response to the node defect in thermally activated remagnetization of magnetic dot array

Baláž

Horváth

Gmitra

2008

Journal of Magnetism and Magnetic Materials

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The influence of nonmagnetic central node defect on dynamical properties of regular square-shaped 5 × 5 segment of magnetic dot array under the thermal activation is investigated via computer simulations. Using stochastic Landau-Lifshitz-Gilbert equation we simulate hysteresis and relaxation processes. The remarkable quantitative and qualitative differences between magnetic dot arrays with nonmagnetic central node defect and magnetic dot arrays without defects have been found.

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Arrays of nanoscale magnetic dots: Fabrication by x-ray interference lithography and characterization

Cited by 91 publications

References 19 publications

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

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

3D THz metamaterials from micro/nanomanufacturing

The dynamical response to the node defect in thermally activated remagnetization of magnetic dot array

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