STRAIN-INDUCED ENHANCED SOLUBILITY OF AU IN EPITAXIAL-FILMS OF FE

The presence of an Au surfactant overlayer allows the growth of high-q uality Fe thin layers on Au(100) at 420 K to a depth of at least 70 An gstrom The surfactant layer can be removed from the surface by gentle ion sputtering. After this removal,Au is still found within the Fe fil m, as judged by a 0.3 eV shift to lower binding energies of the Au 4f photoemission peak. Quantification of the XPS signal indicates that th e total atomic concentration of Au diluted within the Fe layer is simi lar to 3%, i.e. much higher than the bulk solubility at 420 K. We sugg est that relaxation of the strain causes the enhanced solubility of Au in the Fe layer.