Electronic and magnetic properties of the (001) surface of hole-doped manganites

The electronic and magnetic properties of ferromagnetic doped manganites are investigated by means of model tight-binding and self-interaction corrected local spin density (SIC-LSD) approximation calculations. It is found that the surface alone by breaking the cubic symmetry induces a difference in the occupation of the two e(g) orbitals at the surface. We found surface localization of one orbital and hence a change in the Mn valency from four in the bulk to three at the subsurface. Different surface or disordered interface induced localization of the orbitals are considered too with respect to the nature and the strength of the local orbital ordering and magnetic exchange coupling between the surface/interface and the bulklike region. We predict that better tunneling can be achieved in tunnel barriers that favor slightly the occupancy of the Mn e(g(3z)(2)-r(2)) at the interface.