J A M Paddison, B K Rai, A F May, S A Calder, M B Stone, M D Frontzek, A D Christianson, Magnetic Interactions of the Centrosymmetric Skyrmion Material Gd₂PdSi₃, Phys Rev Lett (accepted, in press).

The experimental realization of magnetic skyrmions in centrosymmetric materials has been driven by theoretical understanding of how a delicate balance of anisotropy and frustration can stabilize topological spin structures in applied magnetic fields. Recently, the centrosymmetric material Gd₂PdSi₃ was shown to host a field-induced skyrmion phase, but the skyrmion stabilization mechanism remains unclear. Here, we employ neutron-scattering measurements on an isotopically-enriched polycrystalline Gd₂PdSi₃ sample to quantify the interactions that drive skyrmion formation. Our analysis reveals spatially-extended interactions in triangular planes that are consistent with an RKKY mechanism, and large ferromagnetic inter-planar magnetic interactions that are modulated by the Pd/Si superstructure. The skyrmion phase emerges from a zero-field helical magnetic order with magnetic moments perpendicular to the magnetic propagation vector, indicating that the magnetic dipolar interaction plays a significant role. Our experimental results establish an interaction space that can promote skyrmion formation, facilitating identification and design of centrosymmetric skyrmion materials.