AVS 46th International Symposium
    Magnetic Interfaces and Nanostructures Technical Group Tuesday Sessions
       Session MI-TuA

Paper MI-TuA7
Photoemission Study of Pseudomorphic Fe@sub x@Ni@sub 1-x@ and Co@sub x@Ni@sub 1-x@ Films on Cu(100)

Tuesday, October 26, 1999, 4:00 pm, Room 618/619

Session: Magnetic Spectroscopies
Presenter: M. Hochstrasser, The Pennsylvania State University
Authors: M. Hochstrasser, The Pennsylvania State University
N. Gilman, The Pennsylvania State University
R.F. Willis, The Pennsylvania State University
F.O. Schumann, Lawrence Livermore National Laboratory
J.G. Tobin, Lawrence Livermore National Laboratory
E. Rotenberg, Lawrence Berkeley National Laboratory (Advanced Light Source)
Correspondent: Click to Email
The k-space electronic structure of Fe@sub x@Ni@sub 1-x@ and Co@sub x@Ni@sub 1-x@ alloy films epitaxially grown on Cu(100) has been investigated with changing stoichiometry in angle-resolved photoemission and is compared to the electronic structure of fcc films of Co and Ni, as well as of Cu. We have monitored changes in the Fermi surface with changing stoichiometry and changing magnetic behavior. In the bulk, the magnetic moment deviates strongly from the Slater-Pauling curve at an Fe concentration of 65%, dropping quickly to zero as does the Curie temperature, at which point a structural phase transition from fcc to bcc is observed. Recently, it has been shown that Fe@sub x@Ni@sub 1-x@ films can establish in the fcc phase when grown as ultrathin films on Cu(100).@footnote 1@ The fcc to bcc structural transformation is quenched, but the magnetic instability persists. Furthermore, we investigated with spin-resolved photoemission spectroscopy the regions relevant for the magnetic coupling with changing composition in Fe@sub x@Ni@sub 1-x@ films on Cu(100). We adress the questions: 1. Is there a relationship between the electronic structure and the sudden change in magnetization at a critical composition? 2. How does the Fermi surface evolve in these pseudomorphic alloy films? 3. What is the polarization of the states thought to be responsible for the oscillatory exchange coupling? The measurements show that the sp-band is a prominent feature of the Fermi surface throughout k-space for all of these alloys. A band structure calculation of Ni allows us to identify d-hole pockets arising from holes in the d-band(s) increasing with changing stoichiometry. The states thought to be responsible for the oscillatory exchange coupling, giving rise to giant magentoresistance (GMR) effects, are identified. @FootnoteText@ @footnote 1@ F. Schumann et. al., Phys. Rev. B, 56, 2668 (1997).