AVS 45th International Symposium
    Magnetic Interfaces and Nanostructures Technical Group Thursday Sessions
       Session MI-ThM

Paper MI-ThM9
A Controversy Over the Magnetic Structure of Mn Overlayers on Fe and the Role of Oxygen Impurities@footnote 1@

Thursday, November 5, 1998, 11:00 am, Room 324/325

Session: Magnetic Spectroscopies
Presenter: S. Banerjee, University of Wisconsin, Milwaukee
Authors: S. Banerjee, University of Wisconsin, Milwaukee
W.L. O'Brien, University of Wisconsin, Madison
B.P. Tonner, University of Wisconsin, Milwaukee
Correspondent: Click to Email
The magnetic coupling across the Fe-Mn interface for ultrathin films of Mn grown on Fe has recently been the focus of both experimental and theoretical research efforts, but without substantial agreement. For example, experimental results claim both parallel@footnote 2@ and antiparallel@footnote 3,4@ magnetic coupling between a submonolayer Mn film and the Fe substrate. This disagreement is made even more interesting by a theoretical analysis which shows that the interlayer magnetic coupling between Mn and Fe is very sensitive to both lattice spacing and valence band structure.@footnote 5@ In an effort to better understand the interface magnetic coupling of this model system we have made a series of x-ray magnetic circular dichroism (XMCD) measurements on the Mn-Fe interface for different Mn coverages, on Fe substrates with both the fct and bcc crystal structures. In addition we investigated the effects of small exposures to oxygen on the magnetic order and coupling for coverages up to one monolayer. The Mn/Fe system is extremely reactive, and shows changes in magnetic state with exposures times as low as 10 minutes at 2 X 10@super -10@ Torr. Our findings show that the chemical state of Mn has a tremendous effect on the magnetization at the Fe-Mn interface while the in plane lattice constant and crystal structure do not. The effect of oxygen exposure is to ferromagnetically align the Mn atoms with an orientation antiparallel to the Fe. The intrinsic magnetic state of Mn on Fe, found by extrapolation to zero exposure to contaminating gases, is that of zero magnetic moment at room temperature. @FootnoteText@ @footnote 1@Work supported by the National Science Foundation DMR and performed at the Wisconsin Synchrotron Radiation Center. @footnote 2@S. Andrieu et. al., Phys. Rev. B 57, 1985 (1998). @footnote 3@O. Rader, W. Gudat, D. Schmitz, C. Carbone, and W. Eberhardt, Phys. Rev. B 56, 5461 (1997). @footnote 4@J. Dresselhaus et. al., Phys. Rev. B 56, 5461 (1997). @footnote 5@ R. Wu and A.J. Freeman, Phys. Rev. B 51, 17131 (1995).