2025/04/29 by L. Chaix, J. Robert, Chaix, L. +35
Physics and Astronomy · Materials Science · #Advanced Condensed Matter Physics #Magnetic Properties and Synthesis of Ferrites #Multiferroics and related materials
paper · pdf · doi:10.48550/arxiv.2504.21142
Combining macroscopic measurements, neutron scattering and modeling, we identify in the GeFe2O4 spinel a correlated paramagnetic state resulting from the predominance of third-neighbor antiferromagnetic interactions. These interactions materialize 4 isolated families of triangular planes with 120∘ spins emerging from the underlying pyrochlore lattice. At lower temperatures, a phase transition occurs from this hierarchical spin liquid to a non-coplanar spin texture that is characterized by 6 propagating vectors. This unusual multi-q order is triggered by the presence of weaker interactions up to the sixth neighbors. The system is remarkably successful in coupling the different triangular planes while maintaining their two-dimensional 120∘ order. Our study highlights the hierarchy of interactions involved in GeFe2O4, which is singular among spinel compounds since first-neighbor interactions are only a small fraction of the dominant third neighbor ones.