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

Paper MI-MoA8
Fermi Surfaces and Magnetic Behavior of Thin FeNi Alloy Films

Monday, October 2, 2000, 4:20 pm, Room 206

Session: Thin Films and Multilayers
Presenter: M. Hochstrasser, The Pennsylvania State University
Authors: M. Hochstrasser, The Pennsylvania State University
N.A.R. 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
Correspondent: Click to Email
We report angle-resolved and spin-resolved photoemission measurements of changes in the electronic structure with changing composition of pseudomorphic films of FeNi magnetic alloys grown epitaxially on Cu(100). With x-ray magnetic linear dichroism angle dependent (XMLDAD) 3p core-level photoemission the evolution of the elemental magnetic moments was monitored. In addition, changes occuring in the spin-polarized valence bands were observed with spin-polarized photoemission, together with changes in the k-distribution of states at the Fermi energy. A <110> projection of the Fermi surface shows a delocalized "dogbone" feature due to sp-states and more localized "hotspots" corresponding to the emergence of minority spin d-states. Hybridization between the s p- and d-states occurs at thesse locations on the dogbone indicative to a strong nesting of wavevectors of excitations spanning the Fermi surface. The sp-dogbone states spin polarize with increasing average magnetic moment. Both elemental moments, observe d in XMLDAD, grow with increasing Fe concentration up to a maximum at the Fe concentration of 55%, that on the Fe increasing at a faster rate than the Ni moment. Beyond this point, the Fe moment shows a rapid decline to a "low-spin" value, of the order of that of the Ni monent, which tracks the behavior of the Fe moment but to a smaller degree. Spin-resolved valence band photoemission measurements show first an increase in the exchange splitting of 3d-states, followed by a decline, essentially tracking th e core-level dichrosim. The magnetic instability observed abovethe invar concentration (Fe > 65%) is characterized further by a diffuseness in the spectral distribution and an increased lifetime broadening of mainly minority-spin states, indicative of magnetic non-collinear disorder.