Photoemission study of Fermi surfaces of pseudomorphic Co, Ni, and CoxNi1-x films on Cu(100)

The k-space electronic structure of CoxNi1-x alloy films epitaxially grown on Cu(100) has been investigated with changing stoichiometry in angle-resol ved photoemission, and is compared to the electronic structure of fee films of Co and Ni, and single-crystalline Cu. We have monitored changes in the Fermi surface with changing stoichiometry and changing magnetic behavior. T he measurements show that the sp band is a prominent feature of the Fermi s urface throughout k space for all of the alloys and the magnetic 3d pseudom orphic fee films. A band-structure calculation of Ni allows us to identify d-hole pockets which increase in size with changing stoichiometry. Minority spin states highlight specific regions of k space associated with key span ning vectors that determine the oscillatory exchange coupling, which underp ins the giant magnetoresistance effect in heterostructures. [S0163-1829(99) 03948-X].