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Search equation: ((uid:50002669)) Sort: Author Title Issue date Filter: All documents types Scientific journals - Article - Short communication - Book review - Letter to the editor - Complete issue - OtherBooks - Book published as author, translator, etc. - Collective work published as editor or directorParts of books - Contribution to collective works - Contribution to encyclopedias, dictionaries... - Preface, postface, glossary...Scientific congresses, symposiums and conference proceedings - Unpublished conference - Paper published in a book - Paper published in a journal - PosterScientific presentation in universities or research centersReports - Expert report - Internal report - External report - OtherDissertations and theses - Bachelor/master dissertation - Doctoral thesis - Postdoctoral thesis - OtherLearning materials - Course notes - OtherPatentCartographic materials - Single work - Part of another publicationComputer developments - Textual, factual or bibliographical database - Software - OtherE-prints/Working papers - First made available on ORBilu - Already available on another siteDiverse speeches and writings - Article for general public - Conference given outside the academic context - Speeches/Talks - Other     Unraveling the magnetic softness in Fe–Ni–B-based nanocrystalline material by magnetic small-angle neutron scatteringBersweiler, Mathias ; Adams, Michael Philipp ; Peral Alonso, Inmaculada et alin IUCrJ (2022), 9(1), 65-72Detailed reference viewed: 23 (2 UL) Quantum Skyrmion Lattices in Heisenberg FerromagnetsHaller, Andreas ; Groenendijk, Solofo; Habibi, Alireza et alE-print/Working paper (2021)Skyrmions are topological magnetic textures which can arise in non-centrosymmetric ferromagnetic materials. In most systems experimentally investigated to date, skyrmions emerge as classical objects ... [more ▼]Skyrmions are topological magnetic textures which can arise in non-centrosymmetric ferromagnetic materials. In most systems experimentally investigated to date, skyrmions emerge as classical objects. However, the discovery of skyrmions with nanometer length scales has sparked interest in their quantum properties. Quantum corrections to the classical magnetic textures have already been considered in the semiclassical regime. Here, we go beyond this limit by investigating quantum skyrmions in the deep quantum regime. We use density matrix renormalization group techniques to study two-dimensional spin-1/2 Heisenberg ferromagnets with Dzyaloshinskii-Moriya interactions and discover a broad region in the zero temperature phase diagram which hosts quantum skyrmion lattice ground states. We argue that this novel quantum skyrmion phase can be detected experimentally in the magnetization profile via local magnetic polarization measurements as well as in the spin structure factor measurable via neutron scattering experiments. Finally, we explore the resulting quantum skyrmion state, analyze its real space polarization profile and show that it is a non-classical state featuring entanglement between quasiparticle and environment mainly localized near the boundary spins of the skyrmion. [less ▲]Detailed reference viewed: 15 (0 UL) Magnetic small-angle neutron scattering - a powerful probe of the magnetization configurationBersweiler, Mathias ; Michels, Andreas Scientific Conference (2021, October 16)Detailed reference viewed: 35 (0 UL) Role of higher-order effects in spin-misalignment small-angle neutron scattering of high-pressure torsion nickelOba, Yojiro; Bersweiler, Mathias ; Titov, Ivan et alin Physical Review Materials (2021), 5Detailed reference viewed: 18 (0 UL) Revealing defect-induced spin disorder in nanocrystalline NiBersweiler, Mathias ; Sinaga, Evelyn Pratami ; Peral Alonso, Inmaculada et alin Physical Review Materials (2021), 5(4), 044409Detailed reference viewed: 80 (25 UL) Neutron study of magnetic correlations in rare-earth-free Mn-Bi magnetsMalyeyev, Artem ; Titov, Ivan; Bender, Philipp et alin Physical Review Materials (2021), 5We report the results of an unpolarized small-angle neutron scattering (SANS) study on Mn-Bi-based rare-earth-free permanent magnets. The magnetic SANS cross section is dominated by long-wavelength ... [more ▼]We report the results of an unpolarized small-angle neutron scattering (SANS) study on Mn-Bi-based rare-earth-free permanent magnets. The magnetic SANS cross section is dominated by long-wavelength transversal magnetization fluctuations and has been analyzed in terms of the Guinier-Porod model and the distance distribution function. This provides the radius of gyration which, in the remanent state, ranges between about $220-240 \, \mathrm{nm}$ for the three different alloy compositions investigated. Moreover, computation of the distance distribution function in conjunction with results for the so-called $s$-parameter obtained from the Guinier-Porod model indicate that the magnetic scattering of a Mn$_{45}$Bi$_{55}$ sample has its origin in slightly shape-anisotropic structures. [less ▲]Detailed reference viewed: 64 (9 UL) Magnetic Small-Angle Neutron Scattering. A Probe for Mesoscale Magnetism AnalysisMichels, Andreas Book published by Oxford University Press (2021)Detailed reference viewed: 90 (10 UL) Unraveling Nanostructured Spin Textures in Bulk MagnetsBender, Philipp Florian ; Leliaert, Jonathan; Bersweiler, Mathias et alin Small Science (2021), 1(1), 2000003One of the key challenges in magnetism remains the determination of the nanoscopic magnetization profile within the volume of thick samples, such as permanent ferromagnets. Thanks to the large penetration ... [more ▼]One of the key challenges in magnetism remains the determination of the nanoscopic magnetization profile within the volume of thick samples, such as permanent ferromagnets. Thanks to the large penetration depth of neutrons, magnetic small-angle neutron scattering (SANS) is a powerful technique to characterize bulk samples. The major challenge regarding magnetic SANS is accessing the real-space magnetization vector field from the reciprocal scattering data. In this letter, a fast iterative algorithm is introduced that allows one to extract the underlying two-dimensional magnetic correlation functions from the scattering patterns. This approach is used here to analyze the magnetic microstructure of Nanoperm, a nanocrystalline alloy which is widely used in power electronics due to its extraordinary soft magnetic properties. It can be shown that the computed correlation functions clearly reflect the projection of the three-dimensional magnetization vector field onto the detector plane, which demonstrates that the used methodology can be applied to probe directly spin-textures within bulk samples with nanometer-resolution. This article is protected by copyright. All rights reserved. [less ▲]Detailed reference viewed: 194 (21 UL) Chemical vapor deposition of CoFe2O4 micropillar arrays with enhanced magnetic propertiesAspe, B.; Malyeyev, Artem ; Vakilinejad, A. et alin Journal of Alloys and Compounds (2021), 890Detailed reference viewed: 41 (3 UL) Observation of surface magnons and crystalline electric field shifts in superantiferromagnetic NdCu2 nanoparticlesJefremovas, E. M.; de la Fuente Rodríguez, M.; Damay, F. et alin Physical Review. B, Condensed Matter (2021), 104Detailed reference viewed: 34 (0 UL) Low-Temperature Growth of AlN Films on Magnetostrictive Foils for High-Magnetoelectric-Response Thin-Film CompositesNguyen, T.; Fleming, Y.; Bender, P. et alin ACS Applied Materials and Interfaces (2021), 13Detailed reference viewed: 40 (4 UL) Toward Understanding Complex Spin Textures in Nanoparticles by Magnetic Neutron ScatteringG. Vivas, Laura; Yanes, Rocio; Berkov, Dmitry et alin Physical Review Letters (2020), 125Detailed reference viewed: 69 (4 UL) Magnetic correlations in polycrystalline Tb0.15Co0.85Bersweiler, Mathias ; Bender, Philipp Florian ; Peral Alonso, Inmaculada et alin Journal of Physics: D Applied Physics (2020), 53Detailed reference viewed: 120 (17 UL) Magnetic Guinier lawMichels, Andreas ; Malyeyev, Artem ; Titov, Ivan et alin IUCrJ (2020), 7Small-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: 65 (14 UL) Experimental observation of third-order effect in magnetic small-angle neutron scatteringMetlov, Konstantin L.; Suzuki, Kiyonori; Honecker, Dirk et alin Physical Review. B, Condensed Matter and Materials Physics (2020), 101Detailed reference viewed: 63 (1 UL) Defect-induced Dzyaloshinskii–Moriya interaction in a nanocrystalline two-phase alloyQuan, Yifan; Kohlbrecher, Joachim; Hautle, Patrick et alin Journal of Physics: Condensed Matter (2020), 32Detailed reference viewed: 109 (1 UL) The benefits of a Bayesian analysis for the characterization of magnetic nanoparticlesBersweiler, Mathias ; Rubio, Helena Gavilan; Honecker, Dirk et alin Nanotechnology (2020), 31(43), 435704Magnetic 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: 113 (8 UL) Anisometric mesoscale nuclear and magnetic texture in sintered Nd-Fe-B magnetsTitov, Ivan ; Honecker, Dirk ; Mettus, Denis et alin Physical Review Materials (2020), 4Detailed reference viewed: 79 (7 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), 100Detailed reference viewed: 167 (7 UL) Effect of grain-boundary diffusion process on the geometry of the grain microstructure of Nd−Fe−B nanocrystalline magnetsTitov, Ivan ; Barbieri, Massimiliano; Bender, Philipp Florian et alin Physical Review Materials (2019), 3(084410), Detailed reference viewed: 89 (7 UL)