8,111 research outputs found
Effect of spin-orbit interaction on a magnetic impurity in the vicinity of a surface
We propose a new mechanism for surface-induced magnetic anisotropy to explain
the thickness-dependence of the Kondo resistivity of thin films of dilute
magnetic alloys. The surface anisotropy energy, generated by spin-orbit
coupling on the magnetic impurity itself, is an oscillating function of the
distance d from the surface and decays as 1/d^2. Numerical estimates based on
simple models suggest that this mechanism, unlike its alternatives, gives rise
to an effect of the desired order of magnitude.Comment: 4 pages, 4 figure
Tuning surface metallicity and ferromagnetism by hydrogen adsorption at the polar ZnO(0001) surface
The adsorption of hydrogen on the polar Zn-ended ZnO(0001) surface has been
investigated by density functional {\it ab-initio} calculations. An on top
H(1x1) ordered overlayer with genuine H-Zn chemical bonds is shown to be
energetically favorable. The H covered surface is metallic and spin-polarized,
with a noticeable magnetic moment at the surface region. Lower hydrogen
coverages lead to strengthening of the H-Zn bonds, corrugation of the surface
layer and to an insulating surface. Our results explain experimental
observations of hydrogen adsorption on this surface, and not only predict a
metal-insulator transition, but primarily provide a method to reversible switch
surface magnetism by varying the hydrogen density on the surface.Comment: 4 pages, 3 figure
Reversible enhancement of the magnetism of ultrathin Co films by H adsorption
By means of ab initio calculations, we have investigated the effect of H
adsorption in the structural, electronic and magnetic properties of ultrathin
Co films on Ru(0001). Our calculations predict that H occupies hollow sites
preserving the two-dimensional 3-fold symmetry. The formation of a complete H
overlayer leads to a very stable surface with strong H-Co bonds. H tends to
suppress surface features, in particular, the enhancement of the magnetic
moments of the bare film. The H-induced effects are mostly confined to the Co
atoms bonded to H, independent of the H coverage or of the thickness and the
structure of the Co film. However, for partial H coverages a significant
increase occurs in the magnetic moment for the surface Co atoms not bonded to
H, leading to a net enhancement of surface magnetism.Comment: 6 pages, 4 figures, 3 table
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