Topological surface magnetism and Néel vector control in a magnetoelectric antiferromagnet

Surface magnetism and surface band bending

High-quality bulk single crystals of Cr₂O₃ are grown using a floating-zone (FZ) method (see methods). The crystal shows a clear antiferromagnetic transition at 307 K in the magnetic susceptibility (Fig. 1b and Supplementary Fig. 1b), consistent with previous reports¹⁹. As expected, bulk crystals are free from net remnant magnetizations shown by the linear magnetization curve as a function of applied magnetic field (Supplementary Fig. 1c, d). On the other hand, the polar reflective MCD sensitive to the out-of-plane magnetization shows clear…