Electronic structure and crystalline coherence in Fe/Si multilayers

Soft x-ray fluorescence spectroscopy has been used to examine the electroni c structure of deeply buried silicide thin films that arise in Fe/Si multil ayers. These systems exhibit antiferromagnetic (AF) coupling of the Fe laye rs, despite their lack of a noble metal spacer layer found in most GMR mate rials. Also, the degree of coupling is very dependent on preparation condit ions, especially spacer layer thickness and growth temperature. The valence band spectra are quite different for films with different spacerlayer thic kness yet are very similar for films grown at different growth temperatures . The latter result is surprising since AF coupling is strongly dependent o n growth temperature. Combining near-edge x-ray absorption with the fluores cence data demonstrates that the local bonding structure in the silicide sp acer layer in epitaxial films which exhibit AF coupling are metallic. These results indicate the equal roles of crystalline coherence and electronic s tructure in determining the magnetic properties of these systems.