AVS 51st International Symposium
    Magnetic Interfaces and Nanostructures Friday Sessions
       Session MI-FrM

Paper MI-FrM8
Enhanced Magnetic Moment in Iron Nitride Thin Films

Friday, November 19, 2004, 10:40 am, Room 304A

Session: Advanced Magnetic Data Storage and Thin Film Processing
Presenter: R.A. Lukaszew, University of Toledo
Authors: R.A. Lukaszew, University of Toledo
D. Pearson, University of Toledo
Z. Zhang, University of Toledo
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In magnetism, maximum interest is focused on iron and iron-based alloys because these materials are of greatest practical use. Iron-based alloys are most susceptible to modification by nitrogen, which can turn them from weak to strong ferromagnets. Nitrogen enters 3d metals as an interstitial provoking a dilation of the lattice. The Fe-N system exhibits several phases of technological importance including several Fe-N intestitial compounds with nitrogen ordering. The ordered iron nitrides are metastable compounds which can persist at moderate temperature because of kinetic constraints. In particular, the magnetic properties of the @alpha@"-Fe@sub 16@N@sub 2@ phase have been of interest for both scientists and technologists since it was first discovered to exhibit magnetization as great as 2.4 T, significantly higher than that of @alpha@-Fe. An important issue is the role of nitrogen in enhancing the iron magnetic moment. Current theories explain the enhanced magnetic moment in terms of a reduced moment on the iron sites that are the nearest-neighbours of nitrogen, and an enhanced moment on the more distant sites due to hybridisation of the 3d states of the iron that is a nearest neighbour and charge transfer from the more distant iron @footnote 1@. No polarization of the N atoms is assumed. In order to evaluate the potential of these materials for magnetic recording head as well as to understand the origin of the observed enhanced magnetic moment more detailed research is required. We will present our studies on epitaxial FeN films grown using reactive magnetron sputtering. We will show magnetic characterization of the films, performed using SQUID, MOKE and XMCD. In particular XMCD data indicates that in addition to Fe, N is also polarized in these films. Thus we believe that N polarization may be the primary reason for enhanced magnetic moment in these materials. @FootnoteText@ @footnote 1@. J.M. D. Coey and P. A. I. Smith, J. Mag. Mag. Mat. 200, 405-424 (1999).