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Merkel DG, Bessas D, Zolnai Z, Rüffer R, Chumakov AI, Paddubrouskaya H, Van Haesendonck C, Nagy N, Tóth AL, Deák A. Evolution of magnetism on a curved nano-surface. NANOSCALE 2015; 7:12878-12887. [PMID: 26162007 DOI: 10.1039/c5nr02928g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
To design custom magnetic nanostructures, it is indispensable to acquire precise knowledge about the systems in the nanoscale range where the magnetism forms. In this paper we present the effect of a curved surface on the evolution of magnetism in ultrathin iron films. Nominally 70 Å thick iron films were deposited in 9 steps on 3 different types of templates: (a) a monolayer of silica spheres with 25 nm diameter, (b) a monolayer of silica spheres with 400 nm diameter and (c) for comparison a flat silicon substrate. In situ iron evaporation took place in an ultrahigh vacuum chamber using the molecular beam epitaxy technique. After the evaporation steps, time differential nuclear forward scattering spectra, grazing incidence small angle X-ray scattering images and X-ray reflectivity curves were recorded. In order to reconstruct and visualize the magnetic moment configuration in the iron cap formed on top of the silica spheres, micromagnetic simulations were performed for all iron thicknesses. We found a great influence of the template topography on the onset of magnetism and on the developed magnetic nanostructure. We observed an individual magnetic behaviour for the 400 nm spheres which was modelled by vortex formation and a collective magnetic structure for the 25 nm spheres where magnetic domains spread over several particles. Depth selective nuclear forward scattering measurements showed that the formation of magnetism begins at the top region of the 400 nm spheres in contrast to the 25 nm particles where the magnetism first appears in the region where the spheres are in contact with each other.
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Affiliation(s)
- D G Merkel
- European Synchrotron Radiation Facility, F-38043, Grenoble, France.
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Deák L, Bottyán L, Callens R, Coussement R, Major M, Nasu S, Serdons I, Spiering H, Yoda Y. Stroboscopic detection of nuclear resonance in an arbitrary scattering channel. JOURNAL OF SYNCHROTRON RADIATION 2015; 22:385-392. [PMID: 25723940 DOI: 10.1107/s1600577514026344] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 12/01/2014] [Indexed: 06/04/2023]
Abstract
The theory of heterodyne/stroboscopic detection of nuclear resonance scattering is developed, starting from the total scattering matrix as a product of the matrix of the reference sample and the sample under study. This general approach holds for all dynamical scattering channels. In the forward channel, which has been discussed in detail in the literature, the electronic scattering manifests itself only in an energy-independent diminution of the scattered intensity. In all other channels, complex resonance line shapes of the heterodyne/stroboscopic spectra are encountered, as a result of the interference of electronic and nuclear scattering. The grazing-incidence case will be evaluated and described in detail. Experimental data of classical X-ray reflectivity and their stroboscopically detected resonant counterpart spectra on the [(nat)Fe/(57)Fe]10 isotope periodic multilayer and antiferromagnetic [(57)Fe/Cr]20 superlattice are fitted simultaneously.
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Affiliation(s)
- L Deák
- Wigner RCP, RMKI, POB 49, 1525 Budapest, Hungary
| | - L Bottyán
- Wigner RCP, RMKI, POB 49, 1525 Budapest, Hungary
| | - R Callens
- Instituut voor Kern- en Stralingsfysica, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium
| | - R Coussement
- Instituut voor Kern- en Stralingsfysica, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium
| | - M Major
- Institute for Materials Science, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - S Nasu
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - I Serdons
- Instituut voor Kern- en Stralingsfysica, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium
| | - H Spiering
- Institut für Anorganische und Analytische Chemie, Johannes Gutenberg Universität Mainz, Staudinger Weg 9, D-55099 Mainz, Germany
| | - Y Yoda
- SPring-8 JASRI, 1-1-1 Kouto, Mikazuki-cho, Sayo-gun, Hyogo 679-5198, Japan
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Deák L, Bottyán L, Fülöp T, Kertész G, Nagy DL, Rüffer R, Spiering H, Tanczikó F, Vankó G. Switching reciprocity on and off in a magneto-optical x-ray scattering experiment using nuclear resonance of α-(57)Fe foils. PHYSICAL REVIEW LETTERS 2012; 109:237402. [PMID: 23368265 DOI: 10.1103/physrevlett.109.237402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Indexed: 06/01/2023]
Abstract
Reciprocity is when the scattering amplitude of wave propagation satisfies a symmetry property, connecting a scattering process with an appropriate reversed one. We report on an experiment using nuclear resonance scattering of synchrotron radiation, which demonstrates that magneto-optical materials do not necessarily violate reciprocity. The setting enables us to switch easily between reciprocity and its violation. In the latter case, the exhibited reciprocity violation is orders of magnitude larger than achieved by previous wave scattering experiments.
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Affiliation(s)
- L Deák
- Wigner RCP, RMKI, P.O.B. 49, H-1525 Budapest, Hungary.
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