Changes in the Fermi surface of Cu-Ni and Ag-Mn random alloys deduced from studies of the photoemission from (111) surface states

Abstract

Features are observed in the uv photoemission spectra from (111) faces of Cu-Ni and Ag-Mn random substitutional alloys which arise from Shockley-type surface states located around the ⌈ point of the 2-dimensional Brillouin zone. The variations in intensity of these features and their dispersion have been measured in the ⌈ LWK and ⌈ LUX planes using Arl photons. Since the dimensions of the Fermi surface in the vicinity of the L point are related to the dispersion of the surface state, the results indicate that in the case of Cu-Ni alloys the neck radius around [111] decreases as the bulk concentration of Ni increases, in good agreement with previous investigations using alternative techniques. In Ag-Mn alloys, however, the ϵF−L′2 gap and the neck radius both increase as Mn is added to Ag.