Spintronic devices usually inject spin currents from ferromagnets. An international team has now shown directly that a compensated magnet, Mn5Si3, whose net magnetisation vanishes, can inject spin in a way that breaks time-reversal symmetry. In a lateral spin valve, switching the magnet between its time-reversed states changed the detected spin signal, in two different biasing geometries.
The team interprets the effect as spin-up and spin-down currents of different strengths and directions in a d-wave altermagnet, backed by symmetry analysis and first-principles calculations. QMAT's Tim Kokkeler, from Tero Heikkilä's Condensed Matter Theory group at the University of Jyväskylä, is a co-author. The study involved CIC nanoGUNE in San Sebastián and partners in Spain, the Czech Republic, Germany, France, the UK, Uruguay and Colombia.
The preprint has not yet been peer reviewed.
Figure: Mencos et al., arXiv:2512.17427 (2025), CC BY 4.0