Electronic and crystalline structure at the surface of epitaxial films of DyNi grown on W(110)

The electronic and crystalline structures of thin epitaxial DyNi films grown in situ by codeposition of both constituents onto a W(110) substrate followed by annealing at 500^∘C were studied by angle-resolved valence-band photoemission and low-energy electron diffraction (LEED). The obtained experimental data are in good agreement with results of local-density-approximation calculations in bulk geometry. Further investigations included supercell calculations. According to the latter investigations the observed (3×1) overstructure of the LEED pattern and a Dy $5d$-derived surface state near the Fermi energy are related to a reconstruction of the (001) surface of DyNi resulting from missing Ni rows in the topmost atomic layer. The d-like surface state is a well-known phenomenon for metallic Dy(0001). Similar to the situation in rare-earth metals, it may influence the surface magnetic properties of thin DyNi films.