Monolayer NiI₂ is a prototypical two-dimensional multiferroic, and theory predicts that its properties can be tuned by strain, gating or neighbouring materials. Researchers at Aalto University have now shown experimentally that placing NiI₂ on superconducting NbSe₂ changes its magnetic ground state.

Using low-temperature scanning tunnelling microscopy and spectroscopy, the team found that the metallic substrate renormalises the exchange interactions and drives NiI₂ into a ferromagnetic state. This shows up in Yu–Shiba–Rusinov states, bound states inside the superconducting gap of the substrate, which the authors establish as an in situ probe of 2D magnetism. The work combines Peter Liljeroth's Atomic Scale Physics group with QMAT's Correlated Quantum Materials group (Jose Lado and Adolfo Fumega).

The preprint has not yet been peer reviewed.

Image: QMAT