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   Toward Understanding Complex Spin Textures in Nanoparticles by Magnetic Neutron Scattering; ; et al in Physical Review Letters (2020), 125 Detailed reference viewed: 38 (0 UL)Magnetic correlations in polycrystalline Tb0.15Co0.85Bersweiler, Mathias  ; Bender, Philipp Florian ; Peral Alonso, Inmaculada et alin Journal of Physics: D Applied Physics (2020), 53 Detailed reference viewed: 71 (10 UL) Magnetic Guinier lawMichels, Andreas ; Malyeyev, Artem ; Titov, Ivan et alin IUCrJ (2020), 7 Small-angle scattering of x-rays and neutrons is a routine method for the determination of nanoparticle sizes. The so-called Guinier law represents the low-q approximation for the small-angle scattering ... [more ▼] Small-angle scattering of x-rays and neutrons is a routine method for the determination of nanoparticle sizes. The so-called Guinier law represents the low-q approximation for the small-angle scattering curve from an assembly of particles. The Guinier law has originally been derived for nonmagnetic particle-matrix-type systems, and it is successfully employed for the estimation of particle sizes in various scientific domains (e.g., soft matter physics, biology, colloidal chemistry, materials science). An important prerequisite for it to apply is the presence of a discontinuous interface separating particles and matrix. Here, we introduce the Guinier law for the case of magnetic small-angle neutron scattering (SANS) and experimentally demonstrate its applicability for the example of nanocrystalline cobalt. It is well- known that the magnetic microstructure of nanocrystalline ferromagnets is highly nonuniform on the nanometer length scale and characterized by a spectrum of continuously varying long-wavelength magnetization fluctuations, i.e., these systems do not manifest sharp interfaces in their magnetization profile. The magnetic Guinier radius depends on the applied magnetic field, on the magnetic interactions (exchange, magnetostatics), and on the magnetic anisotropy-field radius, which characterizes the size over which the magnetic anisotropy field is coherently aligned into the same direction. In contrast to the nonmagnetic conventional Guinier law, the magnetic version can be applied to fully dense random-anisotropy-type ferromagnets. [less ▲] Detailed reference viewed: 34 (9 UL)The benefits of a Bayesian analysis for the characterization of magnetic nanoparticlesBersweiler, Mathias ; ; Honecker, Dirk et alin Nanotechnology (2020), 31(43), 435704 Magnetic nanoparticles offer a unique potential for various biomedical applications, but prior to commercial usage a standardized characterization of their structural and magnetic properties is required ... [more ▼] Magnetic nanoparticles offer a unique potential for various biomedical applications, but prior to commercial usage a standardized characterization of their structural and magnetic properties is required. For a thorough characterization, the combination of conventional magnetometry and advanced scattering techniques has shown great potential. In the present work, we characterize a powder sample of high-quality iron oxide nanoparticles that are surrounded with a homogeneous thick silica shell by DC magnetometry and magnetic small-angle neutron scattering (SANS). To retrieve the particle parameters such as their size distribution and saturation magnetization from the data, we apply standard model fits of individual data sets as well as global fits of multiple curves, including a combination of the magnetometry and SANS measurements. We show that by combining a standard least-squares fit with a subsequent Bayesian approach for the data refinement, the probability distributions of the model parameters and their cross correlations can be readily extracted, which enables a direct visual feedback regarding the quality of the fit. This prevents an overfitting of data in case of highly correlated parameters and renders the Bayesian method as an ideal component for a standardized data analysis of magnetic nanoparticle samples. [less ▲] Detailed reference viewed: 86 (7 UL)Anisometric mesoscale nuclear and magnetic texture in sintered Nd-Fe-B magnetsTitov, Ivan ; Honecker, Dirk ; et alin Physical Review Materials (2020), 4 Detailed reference viewed: 42 (7 UL)Defect-induced Dzyaloshinskii–Moriya interaction in a nanocrystalline two-phase alloy; ; et al in Journal of Physics: Condensed Matter (2020), 32 Detailed reference viewed: 73 (1 UL)Experimental observation of third-order effect in magnetic small-angle neutron scattering; ; Honecker, Dirk et alin Physical Review. B, Condensed Matter and Materials Physics (2020), 101 Detailed reference viewed: 36 (1 UL)Size-dependent spatial magnetization profile of Manganese-Zinc ferrite Mn0.2Zn0.2Fe2.6O4 nanoparticlesBersweiler, Mathias ; Bender, Philipp Florian ; Gonzalez Vivas, Laura et alin Physical Review. B (2019), 100 Detailed reference viewed: 120 (3 UL)Effect of grain-boundary diffusion process on the geometry of the grain microstructure of Nd−Fe−B nanocrystalline magnetsTitov, Ivan ; ; Bender, Philipp Florian et alin Physical Review Materials (2019), 3(084410), Detailed reference viewed: 69 (7 UL)Magnetic neutron scattering studies on Nd-Fe-B magnets (Keynote Lecture)Michels, Andreas Scientific Conference (2019, June 05) Detailed reference viewed: 58 (1 UL)Magnetic Guinier LawMalyeyev, Artem ; Michels, Andreas Poster (2019, June) We introduce the Guinier law for the case of magnetic SANS and provide an analysis of experimental data on a Nd-Fe-B-based nanocomposite and on a rare-earth-free MnBi permanent magnet. The robustness of ... [more ▼] We introduce the Guinier law for the case of magnetic SANS and provide an analysis of experimental data on a Nd-Fe-B-based nanocomposite and on a rare-earth-free MnBi permanent magnet. The robustness of this novel approach is discussed and the quantities derived are analyzed in the framework of the existing research literature. [less ▲] Detailed reference viewed: 90 (14 UL)Microstructural-defect-induced Dzyaloshinskii-Moriya interactionMichels, Andreas ; ; Titov, Ivan et alin Physical Review. B, Condensed Matter (2019), 99 Detailed reference viewed: 143 (20 UL)Erratum: Third-order effect in magnetic small-angle neutron scattering by a spatially inhomogeneous medium [Phys. Rev. B 91, 054404 (2015)]; Michels, Andreas in Physical Review. B, Condensed Matter and Materials Physics (2019), 99 Detailed reference viewed: 80 (0 UL)Magnetic small-angle neutron scattering; ; et al in Reviews of Modern Physics (2019), 91 Detailed reference viewed: 101 (9 UL)Evidence for the formation of nanoprecipitates with magnetically disordered regions in bulk Ni50Mn45In5 Heusler alloys; Titov, Ivan ; Malyeyev, Artem et alin Physical Review. B, Condensed Matter and Materials Physics (2019), 99 Detailed reference viewed: 159 (19 UL)Micromagnetic simulations for understanding magnetic SANSMichels, Andreas Scientific Conference (2018, October 29) Detailed reference viewed: 38 (1 UL)Magnetic neutron scattering on nanomagnetsMichels, Andreas Scientific Conference (2018, September 26) Detailed reference viewed: 33 (1 UL)Effect of annealing conditions on the microstructure and magnetic properties of sintered Nd-Fe-B magnets as seen by magnetic small-angle neutron scatteringMichels, Andreas ; Perigo, Elio Alberto ; Titov, Ivan et alScientific Conference (2018, August 29) Detailed reference viewed: 119 (11 UL)Magnetic neutron scattering on bulk ferromagnetsMichels, Andreas Presentation (2018, July 12) Detailed reference viewed: 43 (7 UL)Magnetic SANS is different than nonmagnetic SANSMichels, Andreas Scientific Conference (2018, June 18) Detailed reference viewed: 25 (2 UL) |
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