AVS 49th International Symposium
    Magnetic Interfaces and Nanostructures Thursday Sessions
       Session MI+NS-ThA

Paper MI+NS-ThA3
Magnetic Imaging and Spectroscopy of Fe@sub x@Ni@sub(1-x)@ Thin Films on Cu(111)

Thursday, November 7, 2002, 2:40 pm, Room C-205

Session: Magnetic Imaging
Presenter: Y. Sato, University of California, Davis
Authors: Y. Sato, University of California, Davis
T.F. Johnson, University of California, Davis
S. Chiang, University of California, Davis
M. Hochstrasser, Lawrence Livermore National Laboratory
J.G. Tobin, Lawrence Livermore National Laboratory
A. Scholl, Lawrence Berkeley National Laboratory
J.A. Giacomo, University of California, Davis
D.B. Hoffman, University of California, Davis
Correspondent: Click to Email
We are studying the system of FeNi/Cu(111) to understand the surface/interface magnetism relevant to the application of the giant magnetoresistive effect to magnetic recording heads. We have used X-ray Magnetic Linear Dichroism (XMLD) and Photoemission Electron Microscopy (PEEM) at the Advanced Light Source, and Low Energy Electron Microscopy (LEEM). Using XMLD, the dichroism signals from both the Fe and Ni peaks were measured, and the asymmetries were calculated. Both the Fe and Ni asymmetries as a function of temperature have been fit to the theoretical curve to extract the critical exponent @beta@. Preliminary analysis indicates that for thicker films, the values are consistent with 3D mean-field magnetic models. As a function of Fe concentration x, the total weighted asymmetry, A@sub T@= xA@sub Fe@+(1-x)A@sub Ni@, where A@sub Fe@ and A@sub Ni@ are the respective elemental asymmetries, shows a monotonic increase from 2% to a maximum of 8.5% for x~65%, near the bulk Invar concentration. For higher x, the asymmetry is quenched, indicating a magnetic transition taking place in the film system. This magnetic instability for high x agrees with the trends in Curie temperature as a function of x, as measured from XMLD spectra, PEEM data, and previous work on FeNi/Cu(100).@footnote 1@ The PEEM images show a change in the domain structure of the films for x~42-55%. The domain structures are defined well by 180° domain walls, and their size is much bigger than for other concentrations. The magnetization appears to align along one of the crystal axes. Low Energy Electron Microscopy images of the growth of the films will also be shown. @FootnoteText@ @footnote 1@F.O.Schumann, S.Z.Wu, G.J.Mankey, R.F.Willis Phys.Rev.B 56, 2668 (1997).