Enhancement of Orbital Magnetism at Surfaces: Co on Cu(100)

By combining magnetic circular x-ray dichroism experiments with first principles electronic structure calculations, we demonstrate that the orbital contribution to magnetism can be strongly enhanced at surfaces. This effect is illustrated for Co grown on a Cu(100) surface, where the first layer of Co shows an enhancement of the orbital moment (0.26 μB) by a factor of 2 as compared to the bulk. The lowering of the symmetry at the surface, the enhanced spin moment, and the increased value of the density of states at the Fermi level are factors that generally give the observed enhancements.