acta physica slovaca

Acta Physica Slovaca 57, No.6, 911-1074 (2007) (163 pages)

Advanced nanometer-size structures

Eva Majkovaa, Matej Jergela, Masaki Yamamotob, Toshihide Tsurub, Stefan Lubyb, Peter Siffalovica

  aInstitute of Physics, Slovak Academyh of Sciences,
   84511 Bratislava, Slovakia
  bIMRAM, Tohoku university,
   Katahira, Sendai 980-8577, Japan

Full text: ::pdf :: (received 10 March 2008, accepted 17 March 2008)

Abstract: Solid state physics made a considerable progress towards nanometer- and subnanometer-size structures during the last decade. The structures encompass ultra thin films, multilayers, tubes, pillars, particles, clusters, etc. In this work, we address some of them. In particular, multilayers and spin valves with nm and sub-nm thickness of individual layers and ordered monolayers of nanoparticles are discussed in detail. These structures are at the forefront of further progress in the soft X-ray and extreme ultraviolet optics, spintronics and the whole emerging nanotechnology era. Attention is paid to the design, layer growth control with pi- cometer resolution, interface phenomena and interlayer formation which is also responsible for thermal stability of both multilayers and spin valves. Interfaces are characterized by a full set of parameters including various types of roughness, its lateral and vertical correlations and fractal dimension. For the analyses of interfaces, X-ray diffraction, X-ray reflectivity and diffuse scattering have been elaborated in detail. The results are completed by local methods, like electron and atomic probe microscopies. Layered structures are studied in view of their applications in X-ray and extreme ultraviolet mirrors, giant magnetoresistance and spintron- ics devices. Development of novel nanosized structures with embedded arrays of magnetic nanoparticles is a challenging task nowadays. Magnetic nanoparticles offer a possibility of quantized electron tunneling and additional spin blockade. An ordered array of such nanopar- ticles can be used as natural double tunnel barrier of novel tunnel magnetoresistance devices. The Co, Fe3 O4 , CoFe2 O4 magnetic nanoparticles prepared in colloidal solutions are of main interest for us. The process of spontaneous nanoparticle self-assembly leads to well correlated nanoparticle arrays. Such bottom-up approach presents a fast and cost-effective way of fab- rication of nanoparticle monolayers. It will be shown that the grazing incidence small-angle X-ray scattering is a powerful technique for characterization of nanoparticle arrays, allow- ing in-situ studies of the ordering process. In particular, it can resolve the problem whether the arrays are formed on the substrate surface or on the surface of the drop of the colloidal solution. We hope that tutorial style of our presentation with insight into basic theories and experimental approaches completed by simulations will result in a useful introduction into some areas of the nanometer world.

PACS: 61.10.Eq, 61.46.Df, 72.25.-b, 75.75.+a, 81.15.-z, 81.16.-c, 85.75.-d
Keywords: Multilayers, Interfaces, Magnetic nanoparticles, X-EUV optics, GMR, Spin valves, Nanoparticle self-assembly, X-ray reflectometry, GISAXS

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