In monolayer NiI₂, magnetism and ferroelectricity were recently found to be intertwined, a property known as type-II multiferroicity. Researchers at Aalto University have now shown that this is not a one-off: monolayer NiBr₂ behaves in the same way.

Using scanning tunnelling microscopy, the team imaged atomic-scale ferroelectric domains and confirmed their magnetic origin by reorienting the magnetic order with electric fields and suppressing the polarisation with magnetic fields. The multiferroic state in NiBr₂ is less robust than in the iodide, consistent with modified superexchange and weaker spin–orbit coupling, which suggests these phases can be tuned by chemical substitution. The work comes from Peter Liljeroth's Atomic Scale Physics group at Aalto, with Aleš Cahlík and Antti Karjasilta, and acknowledges support from QMAT.

Figure: Cahlík et al., Adv. Sci. (2026); image from arXiv:2601.20713, CC BY 4.0