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See detailMagnetic SANS is different than nonmagnetic SANS
Michels, Andreas UL

Scientific Conference (2018, June 18)

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See detailMagnetic SANS on bulk ferromagnets
Michels, Andreas UL

Scientific Conference (2016, June 08)

Detailed reference viewed: 58 (8 UL)
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See detailMagnetic SANS on bulk ferromagnets
Michels, Andreas UL

Scientific Conference (2016, September 22)

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See detailMagnetic SANS on bulk magnets
Michels, Andreas UL

Presentation (2013, February 11)

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See detailMagnetic SANS on bulk magnets
Michels, Andreas UL

Presentation (2013)

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See detailMagnetic SANS on nanomagnets
Michels, Andreas UL

Scientific Conference (2013, October)

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See detailMagnetic SANS study of a sintered Nd–Fe–B magnet: Estimation of defect size
Perigo, Elio Alberto UL; Gilbert, Elliot; Michels, Andreas UL

in Acta Materialia (2015), 87

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See detailMagnetic small-angle neutron scattering
Mühlbauer, Sebastian; Honecker, Dirk; Perigo, Elio A. et al

in Reviews of Modern Physics (2019), 91

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See detailMagnetic small-angle neutron scattering by nanocrystalline terbium
Weissmüller, J.; Michels, D.; Michels, Andreas UL et al

in Scripta Materialia (2001), 44(8), 2357-2361

We present an experimental study of the magnetic microstructure in the nanocrystalline hard magnet Tb. Field-dependent SANS data are analyzed quantitatively in terms of the correlation function of the ... [more ▼]

We present an experimental study of the magnetic microstructure in the nanocrystalline hard magnet Tb. Field-dependent SANS data are analyzed quantitatively in terms of the correlation function of the spin misalignment. We find that up to applied fields of several Tesla the magnetization remains ‘locked in’ to the basal planes of the hcp crystal lattice of each individual crystallite; But that the in-plane orientation of the spins is highly nonuniform within each particle. This internal structure can be suppressed by the applied field. [less ▲]

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See detailMagnetic small-angle neutron scattering of bulk ferromagnets
Michels, Andreas UL

in Journal of Physics : Condensed Matter (2014), 26

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See detailMagnetic small-angle neutron scattering on bulk metallic glasses
Mettus, Denis UL; Michels, Andreas UL; Honecker, Dirk et al

Scientific Conference (2016, March 08)

Bulk metallic glasses (BMG) are amorphous solids which are very well known for their excellent mechanical properties. In this contribution, we focus on their magnetic behavior and we discuss the influence ... [more ▼]

Bulk metallic glasses (BMG) are amorphous solids which are very well known for their excellent mechanical properties. In this contribution, we focus on their magnetic behavior and we discuss the influence of mechanical deformation on the magnetic microstructure as seen by magnetic-field-dependent small-angle neutron scattering (SANS). This technique allows one to investigate the spin distribution in the bulk of the material and on the nanometer length scale. We present and compare the results of unpolarized SANS on various BMG samples (as-cast, aged, deformed) and we analyze the SANS cross section in real space by computing the correlation function. [less ▲]

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See detailMAGNETIC SMALL-ANGLE NEUTRON SCATTERING ON BULK METALLIC GLASSES
Mettus, Denis UL; Michels, Andreas UL; Birringer, Rainer et al

Scientific Conference (2017, July 03)

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See detailMagnetic small-angle neutron scattering on bulk metallic glasses
Mettus, Denis UL

Doctoral thesis (2018)

The present PhD thesis is devoted to the exploration of the use of the magnetic small-angle neutron scattering (SANS) technique for analyzing the magnetic microstructure of bulk magnetic materials. More ... [more ▼]

The present PhD thesis is devoted to the exploration of the use of the magnetic small-angle neutron scattering (SANS) technique for analyzing the magnetic microstructure of bulk magnetic materials. More specifically, magnetic-field-dependent SANS has been utilized to study the magnetic microstructure of bulk metallic glasses (BMGs). The magnetic scattering is compared for soft magnetic and hard magnetic compositions in different mechanically treated states. On the basis of the continuum theory of micromagnetics, the correlation function of the spin-misalignment SANS cross section is computed and analyzed as a function of various external and material parameters. Analysis of the experimental correlation functions of the BMG reveals the existence of field-dependent anisotropic long-wavelength magnetization fluctuations on a scale of a few tens of nanometers. As a second aspect of this PhD work, we have explored the impact of the Dzyaloshinski-Moriya interaction on the elastic magnetic SANS cross section of microstructural-defect-rich materials. The effect was demonstrated by measuring polarized SANS on a nanocrystalline terbium sample and on a cold-rolled polycrystalline cobalt sample. [less ▲]

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See detailMagnetic small-angle neutron scattering on bulk metallic glasses: A feasibility study for imaging displacement fields
Mettus, Denis UL; Deckarm, Michael; Leibner, Andreas et al

in Physical Review Materials (2017), 1

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See detailMagnetic small-angle neutron scattering on nanomagnets
Michels, Andreas UL

Scientific Conference (2012)

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See detailMagnetic small-angle neutron scattering: beyond the particle-matrix concept
Michels, Andreas UL

Poster (2015, September)

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See detailMagnetic structure factor of correlated moments in small-angle neutron scattering
Honecker, Dirk UL; Fernández Barquín, Luis; Bender, Philipp Florian UL

in Physical Review. B, Condensed Matter and Materials Physics (2020), 101(13), 134401

The interplay between structural and magnetic properties of nanostructured magnetic materials allows one to realize unconventional magnetic effects, which results in a demand for experimental techniques ... [more ▼]

The interplay between structural and magnetic properties of nanostructured magnetic materials allows one to realize unconventional magnetic effects, which results in a demand for experimental techniques to determine the magnetization profile with nanoscale resolution. Magnetic small-angle neutron scattering (SANS) probes both the chemical and magnetic nanostructure and is thus a powerful technique, e.g., for the characterization of magnetic nanoparticles. Here, we show that the conventionally used particle-matrix approach to describe SANS of magnetic particle assemblies, however, leads to a flawed interpretation. As a remedy, we provide general expressions for the field-dependent two-dimensional magnetic SANS cross section of correlated moments. It is shown that for structurally disordered ensembles the magnetic structure factor is in general, and contrary to common assumptions, (i) anisotropic also in zero field and (ii) that even in saturation the magnetic structure factor deviates from the nuclear one. These theoretical predictions explain qualitatively the intriguing experimental, polarized SANS data of an ensemble of dipolar-coupled iron oxide nanoparticles. [less ▲]

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See detailMagnetic-field-dependent optical transmission of nickel nanorod colloidal dispersions
Klein, Tobias; Laptev, Aleksej; Günther, Annegret UL et al

in Journal of Applied Physics (2009), 106

Aqueous dispersions of nickel nanorods, ~13 nm in diameter and 40–160 nm in length, were synthesized using ac electrodeposition into porous alumina templates. The nanorods in suspension can be aligned by ... [more ▼]

Aqueous dispersions of nickel nanorods, ~13 nm in diameter and 40–160 nm in length, were synthesized using ac electrodeposition into porous alumina templates. The nanorods in suspension can be aligned by modest magnetic fields, which leads to a change in the optical transmittance of the dispersion. Optical transmission measurements with polarized and unpolarized light as a function of magnetic field were performed on suspensions of different particle concentration and varying aspect ratio of the nanoparticles. The experimental results were compared with a theoretical model in which the optical absorption of the nanorods is calculated from the polarizability of prolate ellipsoids in the quasistatic approximation. The magnetic field dependence is introduced in terms of the static orientational distribution function of magnetic moments in an external field. In addition, the relaxation dynamics of the optical transmission was studied, which allowed us to determine the rotational diffusion coefficient of the nanorods in suspension. [less ▲]

Detailed reference viewed: 92 (2 UL)