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

Paper MI-TuA8
Magnetic Properties of Fe-based Alloys

Tuesday, October 26, 1999, 4:20 pm, Room 618/619

Session: Magnetic Spectroscopies
Presenter: F.O. Schumann, Lawrence Livermore National Laboratory
Authors: F.O. Schumann, Lawrence Livermore National Laboratory
J.G. Tobin, Lawrence Livermore National Laboratory
Correspondent: Click to Email
The magnetic properties of fcc Fe@sub x@Ni@sub 1-x@ and Fe@sub x@Co@sub 1-x@ alloys grown on Cu(100)were investigated in an element-specific fashion.The technique employed was linear dichoism in photoemission (MLDAD), which by varying the chirality can also determine the magnetization axis. We observed a different behavior for the two alloys at Fe concentrations above 60%. At this concentration the Fe@sub x@Ni@sub 1-x@ alloy shows a strong reduction of the Fe dichroism associated with the invar instability.@footnote 1@ This is in contrast to the Fe@sub x@Co@sub 1-x@ alloy, where the Fe dichroism stays essentially constant across the concentration.This would indicate that a volume-moment instability is absent, which disagrees with a recent theoretical study.@footnote 2@ Despite these differences both systems show a change of the easy axis at roughly the same electron count.For small Fe concentrations the easy axis is in-plane along the [110] direction. This changes into the [100] direction at Fe@sub 60@Ni@sub 40@, which is at 0.8 excess electrons per atom when compared with Fe.This is different to the bulk, where a change occurs at Fe@sub 35@Ni@sub 65@. We find the easy axis change for Fe@sub x@Co@sub 1-x@ to occur at 35% Fe. This would be equivalent to 0.65 excess electrons when compared with Fe. @FootnoteText@ @footnote 1@ F.O. Schumann et al., Phys. Rev. Lett 79,5166 (1997). @footnote 2@ P.James et al., Phys. Rev. B 59,419 (1999).