AVS 47th International Symposium
    Magnetic Interfaces and Nanostructures Monday Sessions
       Session MI-MoM

Paper MI-MoM4
On the Evolution of Magnetic Moments of Fe in FeCo(100) & FeNi(100) Alloy Films

Monday, October 2, 2000, 9:20 am, Room 206

Session: Magnetic Spectroscopies
Presenter: N.A.R. Gilman, Pennsylvania State University
Authors: N.A.R. Gilman, Pennsylvania State University
R. Zhang, Pennsylvania State University
R.F. Willis, Pennsylvania State University
M. Hochstrasser, Lawrence Livermore National Laboratory
J.G. Tobin, Lawrence Livermore National Laboratory
Correspondent: Click to Email
We report on the variation of the local magnetic moments with changing composition in Fe@sub x@Co@sub 1-x@ and Fe@sub x@Ni@sub 1-x@ alloy films grown epitaxially on fcc Cu(100). The elemental magnetic moments were determined from magnetic-field-induced intensity asymmetry observed in angle-dependent photoelectron spectroscopy of the 3p core-levels of the constituent atoms - "x-ray magnetic dichroism.@footnote 1@ Both the Fe and the Ni moments change in magnitude with changing composition of FeNi alloys.@footnote 2@ The 'stoichiometrically averaged moment' follows the Slater-Pauling curve up to a critical filling of the 3d bands (corresponding to ~2.5 holes in the minority-spin d-band) at which point it collapses to a lower spin-state ('Invar' effect). This is caused by a sudden change in the Fe local moment. This magnetic instability is predicted theoretically independent of what element the Fe is alloyed with ie, a similar collapse is expected for FeCo alloys at the same critical filling of the d-bands.@footnote 3@ However, to date, no such collapse of the Fe moment has been observed in similarly grown FeCo alloy films with fcc-like pseudomorphic structure. In this paper, we present new results comparing the evolution of the Fe moments in FeNi and FeCo fcc pseudomorphic films grown on Cu(100). Simultaneously, we monitor the distribution of states in momentum space at the Fermi energy. The Fermi surface topology confirms that the films are of fcc symmetry, although tetragonal distortion occurs with increasing Fe moment. The dichotomy in the magnetic behavior is discussed in the light of these, and other recent results. @FootnoteText@ @footnote 1@ C. Roth et al., Phys. Rev. Lett. 70, 3479 (1993). @footnote 2@ R.F. Willis et al., Phys. Rev. B, in press (2000) @footnote 3@ P. James et al., Phys. Rev. B 59, 419 (1999).