Unveiling the anisotropic fractal magnetic domain structure in bulk crystals of antiskyrmion host (Fe,Ni,Pd)₃P by small-angle neutron scattering

Abstract

Intermetallic Pd-doped (Fe,Ni)3P, which crystallizes in a non-centrosymmetric tetragonal structure with S 4 symmetry, has recently been discovered to host magnetic antiskyrmions, antivortex-like topological spin textures. In this material, uniaxial magnetic anisotropy and dipolar interactions play a significant role, giving rise to finely branched magnetic domain patterns near the surface of bulk crystals, as revealed by a previous magnetic force microscopy (MFM) measurement. However, small-angle neutron scattering (SANS) is a more suitable method for characterizing bulk properties and fractal structures on the mesoscopic length scale. In this study, using SANS and MFM, the magnetic domain structure in bulk single crystals of (Fe0.63Ni0.30Pd0.07)3P is quantitatively investigated. The SANS results demonstrate that the magnetic domain structure exhibits anisotropic fractal character on length scales down to the width of the magnetic domain walls. The fractal features are gradually lost in magnetic fields, and different field dependencies are observed at 300 and 2 K due to a temperature-dependent anisotropy. This study quantifies the fractality of the highly anisotropic magnetic domain structures in an antiskyrmion material, and highlights the versatility of SANS for the study of fractal structures in magnetic systems.

Neutron Instrument Concepts for a High Intensity Moderator at the European Spallation Source

“…The conceptual designs presented for SANS aim to complement the two instruments under-construction at ESS, LoKI and SKADI, in reaching lower minimum scattering vector values Q min while maintaining high resolution, providing access to larger length-scale structures and thus studies of, for example, mesoscopic aggregates 16 , biological macromolecules such as RNA-protein complexes 17 , type-II superconductors featuring flux line lattices 18 , as well as skyrmion lattices and noncollinear spin structures 19,20 . A large total Q-range coverage is beneficial to studying multi-scale structures, including complex fluids 21 , nanocomposites 22 , and hierarchical materials 23 containing features spanning a broad range of length scales.…”

Neutron instrument concepts for a high intensity moderator at the European spallation source

“…The conceptual designs presented for SANS aim to complement the two instruments under-construction at ESS, LoKI and SKADI, in reaching lower minimum scattering vector values Q min while maintaining high resolution, providing access to larger length-scale structures and thus studies of, for example, mesoscopic aggregates 17 , biological macromolecules such as RNA-protein complexes 18 , type-II superconductors featuring flux line lattices 19 , as well as skyrmion lattices and noncollinear spin structures 20,21 . A large total Q-range coverage is beneficial to studying multi-scale structures, including complex fluids 22 , nanocomposites 23 , and hierarchical materials 24 containing features spanning a broad range of length scales.…”

Skyrmion‐Excited Spin‐Wave Fractal Networks

“…A microwave-frequency excitation is applied to a thin film of hybrid skyrmions, driving them into resonant gyration and causing spin-wave emissions. The magnetic structure is captured using small-angle neutron scattering (SANS); SANS has been a critical tool in the investigation of skyrmions, [22][23][24][25] spin waves, [26][27][28][29][30][31] and fractals, [32,33] but, as an elastic scattering tool, is not typically used to investigate dynamics. At resonance the SANS pattern shows significant changes, including notably the emergence of a new diffraction feature at very small angles, which is attributed to the spin waves.…”