IN²UB INTERNATIONAL RESEARCH SEMINARS
Small-Angle Neutron Scattering as a Tool to Study Spin Textures in Magnetic Nanomaterials
By, Prof. Andreas Michels, Department of Physics and Materials Science, University of Luxembourg
Date: March 26th, 2026 at 12.00h
Venue: Aula Magna Enric Casassas (Faculties of Physics and Chemistry UB)
(Chaired by Prof. Xavier Batlle, IN²UB and Faculty of Physics)
Abstract
Understanding the complex magnetic microstructure of nanomaterials—and its connection to bulk magnetic behavior—requires the complementary strengths of experimental characterization and computational modeling. Among the available techniques, magnetic small-angle neutron scattering (SANS) is particularly powerful, as it provides direct access to intricate spin textures on mesoscopic length scales (~1–1000 nm) deep within the bulk of magnetic materials [1]. Extensive SANS studies have revealed a wide variety of nonuniform spin configurations in nanostructured magnets, ranging from quasi-uniform and canted states to vortex-like and core–shell-type arrangements [1], underscoring the remarkable diversity of nanoscale magnetic textures. In parallel, micromagnetic simulations have become indispensable for predicting mesoscale spin structures and their corresponding scattering signatures. These simulations account for key factors such as particle size and shape, structural defects, and competing magnetic interactions that govern the magnetic ground state of nanoscaled systems. In this combined theoretical and experimental talk, we discuss neutron-scattering signatures associated with several characteristic features of the magnetic microstructure in nanomaterials. These include dipolar-energy-driven vortex states in magnetic nanoparticles [2]; the influence of the Dzyaloshinskii–Moriya interaction [3] and surface anisotropy [4]; characteristic signatures arising from hopfion textures [5]; the observation of scaling [6]; and the experimental observation of a recently predicted spin-disorder-induced angular anisotropy in the polarized neutron-scattering cross section [7].
References
[1] A. Michels, Magnetic Small-Angle Neutron Scattering (Oxford University Press, Oxford, 2021). [2] L.G. Vivas, R. Yanes, D. Berkov, S. Erokhin, M. Bersweiler, D. Honecker, P. Bender, A. Michels, Phys. Rev. Lett. 125, 117201 (2020). [3] E.P. Sinaga, M.P. Adams, E.H. Hasdeo, A. Michels, Phys. Rev. B 110, 054404 (2024). [4] M.P. Adams, E.P. Sinaga, H. Kachkachi, A. Michels, Phys. Rev. B 109, 024429 (2024). [5] K.L. Metlov and A. Michels, Phys. Rev. B 109, L220408 (2024). [6] V. Rai and A. Michels, Phys. Rev. B 112, 144403 (2025). [7] I. Titov, M. Bersweiler, M.P. Adams, E.P. Sinaga, V. Rai, Š. Liščák, M. Lahr, T.L. Schmidt, V.M. Kuchkin, A. Haller, K. Suzuki, N.-J. Steinke, D. Alba Venero, D. Honecker, J. Kohlbrecher, L.F. Barquin, and A. Michels, Phys. Rev. Lett. 135, 196706 (2025).
About the Author
Andreas Michels received his doctoral degree in 2001 from the Universität des Saarlandes, Germany. Following postdoctoral appointments at the Forschungszentrum Karlsruhe (Germany), the Paul Scherrer Institute (Switzerland), and Monash University (Australia), he completed his habilitation in 2008, also at the Universität des Saarlandes. As an ATTRACT research fellow of the National Research Fund of Luxembourg, he established a research group in neutron scattering and magnetic materials within the Department of Physics and Materials Science at the University of Luxembourg, where he is now a Full Professor. His research focuses on magnetic small-angle neutron scattering (SANS). This includes both experimental investigations of spin structures in magnetic materials—such as Nd–Fe–B permanent magnets, magnetic nanoparticles, and topological spin textures—and theoretical and computational work aimed at advancing the fundamental understanding of magnetic SANS.