Time-reversal-symmetry-breaking spin injection from a compensated magnet.

Switching time-reversed magnetic states of Mn5Si3 in lateral spin-valve devices reverses the detected spin signal, showing spin injection that breaks time-reversal symmetry.

• Why it matters: Conventional spin injection depends on net magnetization or relativistic effects, leaving a gap for generating spin currents from compensated magnets with vanishing net magnetization.
• What they did: The study electrically injects spins from Mn5Si3 into a non-magnetic channel and detects propagation at a spatially separated ferromagnetic electrode, using two biasing geometries plus symmetry analysis, first-principles calculations, and spin-transport modelling.
• The result: Calculations give spin polarizations of 6.5–10% and spin-transport modelling indicates spin diffusion lengths of 50–130 nm, consistent with altermagnetic order enabling spintronic functionality without net magnetization.