EXAFS and multiple scattering theory as powerful tools to determine complex structures: application to Mn films grown on Ir

摘要

Int his paper, extended X-ray absorption fine structure (EXAFS) is used to determine the structure of Mn films grown on (001) and (111) fcc Ir lattices by molecular beam epitaxy. As Mn can adopt different structures with small distance differences between first and second neighbours, the usual fourier treatment is not appropriate to determien the Mn structures. We consequently used the multiple scattering theory in order to calculate the EXAFS oscillations. The Mn structures were thus determined by a comparison between simulated and experimental EXAFS spectra. For thin Mn films, Mn was found to grow in trigonal and tetragonal structures on (111) and (001) Ir lattices respectively. For thick Mn films, Mn relaxes to the Mn alpha structure. Finally, the (3~(1/2) x 3~(1/2))R30 deg superstructure of Mn films grown on (111) Ir is shown to come from the epitaxy of a mixed fcc and Mn alph structures and not from the occurrence of Mn Laves phases like Cu_2Mg or Zn_2Mg as assumed by several authors.