Two- and three-dimensional band structure of ultrathin Ni on Cu(001)

Abstract

The momentum-resolved electronic structure of ultrathin films of Ni on Cu(001) is investigated by angle-resolved photoemission in the thickness range between 2 and 6 monolayers and by first-principles slab calculations. While the $sp$-band Fermi surface of Ni shows a full three-dimensional bulklike topology down to the thinnest films, the $d$-band Fermi surface rearranges from a bulklike configuration in the thick films to a two-dimensional topology in the thinnest films. The reduced number of $d$ holes in the thin films is explained with the rearrangement of the characteristic $K$-point lobe of the Ni Fermi surface.