On the magnetic contribution of itinerant electrons to neutron diffraction in the topological antiferromagnet CeAlGe

Abstract: We report a neutron diffraction study of the magnetic structure of CeAlGe, a candidate topological semimetal that hosts a non-collinear, multi-$\mathbf{k}$ magnetic phase. By measuring both low- and high-momentum-transfer magnetic Bragg peaks within a single experimental setup, we refine a magnetic structure model based solely on localized Ce moments. This model, which differs from that obtained using only high-$Q$ data, quantitatively reproduces the observed intensities, including the $(000)$ zeroth-order magnetic satellites that are especially sensitive to subtle components of the modulation. While a contribution from itinerant electrons to the zeroth satellite cannot be definitively excluded, our analysis reveals no unambiguous evidence for such effects within experimental uncertainty. The refined magnetic structures exhibit topologically nontrivial winding patterns, derived from the fitted magnetic parameters, that support localized, particle-like spin textures with half-integer topological charges. These features provide a natural microscopic origin for the observed topological Hall effect, establishing CeAlGe as a model system where magnetism and topology are intimately linked.