Surface electronic structure of Co thin films on Cu(111)

MARÍA ANDREA BARRAL; ANA MARÍA LLOIS; MARIANA WEISSMANN

PHYSICA B - CONDENSED MATTER

Elsevier

Lugar: Amsterdan; Año: 2004 vol. 354 p. 161 - 165

0921-4526

There has been some controversy regarding the Scanning tunneling microscopy (STM) spectra of Co overlayers on Cu(111). Recent experiments (Phys.Rev.Lett. 90 (2003) 236801; Phys. Rev.Lett. 92 (2004) 57202) .nd a peak 0.4 eV below the Fermi energy, at the onset energy of the Cu(111) surface state, while the previous work (Phys.Rev.Lett.85 (2000) 4365) found two peaks, one 1 eV below the Fermi level and the other 0.5 eV above it. To address this problem we have performed both ab initio and parameterized tight-binding calculations for a Cu(111) slab coated with Co layers. The parameterized calculations allow larger unit cells and a better representation of the spill over region.The basis set used contains s, p and d orbitals and also extra s orbitals near the surface for the spill over.Our results for the local density of states at the site of the extra s orbital and at the Co surface site reproduce the feature at -0:4 eV, which also appears in pure Co slabs, and which is, therefore, not related to the Cu(111) surface state.