AVS 46th International Symposium
    Magnetic Interfaces and Nanostructures Technical Group Friday Sessions
       Session MI-FrM

Paper MI-FrM3
Interrelation of Morphology and Structure in Ultrathin Magnetic fcc FeCo Alloy Films on Cu(001)

Friday, October 29, 1999, 9:00 am, Room 618/619

Session: Magnetic Thin Films
Presenter: W. Kuch, Max-Planck-Institut für Mikrostrukturphysik, Germany
Authors: W. Kuch, Max-Planck-Institut für Mikrostrukturphysik, Germany
A. Dittschar, Max-Planck-Institut für Mikrostrukturphysik, Germany
M. Zharnikov, Universität Heidelberg, Germany
C.M. Schneider, Institut für Festkörper- und Werkstofforschung Dresden, Germany
Correspondent: Click to Email
Chemically random epitaxial ultrathin alloy films allow the study of correlation between morphology, structure, and magnetism for continuously varying structural parameters. This can be achieved if variation of the film composition leads to a continuous alteration of film properties such as the lattice constant and the average magnetic moment. We present a multi-technique investigation of structure, morphology, and magnetism of epitaxial Fe@sub x@Co@sub 1-x@ alloy ultrathin films grown on Cu(001) over the whole composition range up to thicknesses of 9 ML. The films grow at room temperature in a distorted fcc structure with random chemical order. The amount and sign of the distortion depend on thickness and composition. Below 60-70% Fe content the alloy films are smooth and tetragonally compressed in the vertical direction in the interior of the films, with tetragonally expanded layers at the surface. The strain is continuously reduced with increasing Fe concentration, and at 60-70% Fe content the interior of the films reaches the unstrained fcc structure. For higher Fe concentrations the occurrence of several superstructures is observed, which are attributed to regular structural rearrangements. At the same time the roughness of films with more than 4-6 ML is significantly enhanced. This is discussed in terms of the vertical strain at Fe concentrations above 70%, the sign of which is reversed with respect to lower Fe concentrations, leading to tetragonally expanded layers. No indications for the presence of low-moment fcc Fe were found in any of the films.