Magnetism in Cr2O3 Thin Films: An Ab Initio Study

The magnetism of Cr₂O₃ thin films on α-Al₂O₃ is investigated using first-principle calculations by considering three Cr₂O₃ films having thicknesses of 4.1 Å (I), 6.7 Å (II), and 10.9 Å (III) and comparing the spin structures of free films with those on the substrate. For the free films, we find that I is ferromagnetic (FM), while II and III are antiferromagnetic (AFM). On the substrate, the Cr₂O₃ film I is also FM. Films II and III remain basically AFM, although the spins of the top Cr layers change sign in both films, creating a ferrimagnet with a small uncompensated net moment.