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arXiv · 2604.02824

Disorder-induced chirality in superconductor-ferromagnet heterostructures revealed by neutron scattering and multiscale modeling

Annika Stellhorn·Juan G. C. Palma·Alicia Backs·Anders Bergman·Angela B. Klautau·Emmanuel Kentzinger·Connie Bednarski-Meinke·Steffen Tober·Elizabeth Blackburn·Juri Barthel·Nina-Juliane Steinke·Helena M. Petrilli·Ivan P. Miranda
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Abstract

Chirality in superconductor-ferromagnet hybrids strongly influences phenomena such as the observable signatures of long-range triplet superconductivity, but its microscopic origin in nominally centrosymmetric ferromagnets is still unclear. Here, we combine structural characterization, polarization-analyzed grazing-incidence small-angle neutron scattering (PA-GISANS), first-principles calculations, and deep-learning-assisted multiscale modeling to study FePd and Nb/FePd heterostructures. Experimentally, we observe partial L1$_0$ order, atomic intermixing, anti-phase boundaries, and a depth-dependent defect gradient across the FePd layer, together with a finite net magnetic chirality at room temperature. The GISANS asymmetry indicates that the main chiral contribution lies in-plane, with an additional out-of-plane component associated with depth-dependent magnetic inhomogeneity. Theoretically, we show that chemical disorder in FePd, especially when combined with a compositional gradient, produces finite Dzyaloshinskii-Moriya interactions and stabilizes chiral finite-$\mathbf{q}$ magnetic modulations with mixed Bloch-N\'eel character. In the mesoscopic model, the resulting in-plane modulation length approaches the experimentally observed range. These results identify disorder and compositional gradients as intrinsic microscopic sources of net chirality in FePd-based films, showing that the observed chirality does not arise only from interface effects.

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Annika Stellhorn, Juan G. C. Palma, Alicia Backs, Anders Bergman, Angela B. Klautau, Emmanuel Kentzinger, Connie Bednarski-Meinke, Steffen Tober, Elizabeth Blackburn, Juri Barthel, Nina-Juliane Steinke, Helena M. Petrilli, Ivan P. Miranda. 2026-04-03. Disorder-induced chirality in superconductor-ferromagnet heterostructures revealed by neutron scattering and multiscale modeling. https://arxiv.org/abs/2604.02824

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