Ab initio study of the structural, electronic, and magnetic properties of MnO(100) and MnO(110)

The structural, electronic, and magnetic properties of the MnO(100) and (110) surfaces were studied within the standard approximation of Perdew, Burke, and Ernzerhof (PBE) and the PBE+U approach. For the (100) surface, the surface layers relax inwards for both sets of calculations. For the (110) surface an electronically driven missing row reconstruction is predicted which significantly lowers the surface energy. For all cases, the O surface atoms relax outwards in comparison to Mn, inducing a buckling of the surface layers. The antiferromagnetic type II ordering of the bulk phase is conserved for both surfaces, the local magnetic moments of Mn exhibit no change with respect to the bulk values. The magnetic ordering at the surfaces is studied in terms of the Heisenberg model and the calculated exchange coupling constants as derived from the ab initio data are significantly enhanced at the surface with respect to the bulk.