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arXiv · 2605.20029

Vortex order in magnetic frustrated GeNi$_2$O$_4$ and GeCo$_2$O$_4$ spinels

K. Beauvois·J. Robert·M. Songvilay·J. Ollivier·B. Fåk·E. Ressouche·N. Qureshi·R. Ballou·S. Petit·S. Lenne·P. Manuel·S. DeBrion·P. Strobel·V. Simonet
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Abstract

In the search for new spin textures based on singular magnetic objects like Bloch-points or vortices, spinel compounds emerge as an interesting playground due to the interplay between magnetic anisotropy and complex interactions that extend well beyond first neighbors on a pyrochlore lattice. Based on an exploration of the exchange interaction phase diagrams of members of the Ge$B_2$O$_4$ family with $B$=Co and Ni, we show, using simultaneous modeling of inelastic neutron scattering measurements and single-crystal neutron diffraction data, that a 2-$k$ magnetic structure may be stabilized in these compounds. This leads to a short period spin vortex crystal, a variant induced by the magnetic anisotropy of the 3-$k$ Bloch-point structure predicted for isotropic spins. Our study rationalizes the formation of these multi-$k$ spin textures in frustrated antiferromagnets, as well as their anisotropy-dependent evolution.

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K. Beauvois, J. Robert, M. Songvilay, J. Ollivier, B. Fåk, E. Ressouche, N. Qureshi, R. Ballou, S. Petit, S. Lenne, P. Manuel, S. DeBrion, P. Strobel, V. Simonet. 2026-05-19. Vortex order in magnetic frustrated GeNi$_2$O$_4$ and GeCo$_2$O$_4$ spinels. https://arxiv.org/abs/2605.20029

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