Researchers demonstrate atomic-scale spin sensing in quantum material

Researchers demonstrated a spin-sensitive scanning tunnelling microscopy probe that provides atomic-scale evidence of two-dimensional d-wave altermagnetism on the surface of KV2Se2O, a Nature paper reports. Altermagnets have electronic states with alternating spin polarization despite having zero net magnetization. The probe uses helical edge modes of α-Bi4Br4 to distinguish spin responses. Atomic mapping, field-dependent spectroscopy and interference imaging supplied converging evidence across real and momentum space. The findings establish a demonstrated route for atomic-scale spin sensing in quantum materials, with the observed magnetic order located in the material's surface layer.