Proximity Length of Emergent Fields in Spin‑Ice/Metal Heterostructures

Non-coplanar spin textures generate an “emergent magnetic field” that drives transversal electron motion, leading to the topological Hall effect (THE). Conventional studies of THE are limited to metallic magnets. To expand the materials platform, we have recently investigated a novel proximity-induced THE, where the emergent field from a magnetic insulator propagates into an adjacent non-magnetic conductor.

We have fabricated heterostructures composed of the spin-ice insulator Dy₂Ti₂O₇ and the non-magnetic conductor (Pb_0.9Sr_0.1)₂Ru₂O_6.5. Magnetotransport measurements at 2 K reveal a non-linear Hall effect that cannot be attributed to the conventional anomalous Hall effect being proportional to a macroscopic magnetization. This non-linear component is successfully explained within the framework of THE, reflecting the sign reversal of the emergent field associated with the spin transition in the Dy₂Ti₂O₇ layer. Furthermore, systematic thickness control of the (Pb_0.9Sr_0.1)₂Ru₂O_6.5 layers enables the estimation of the decay length of the THE signal, which is found to be approximately 2–3 nm.