AVS 49th International Symposium
    Magnetic Interfaces and Nanostructures Friday Sessions
       Session MI+TF-FrM

Paper MI+TF-FrM9
Structure and Magnetic Properties of Thin Fe Films Grown on InAs(100)

Friday, November 8, 2002, 11:00 am, Room C-205

Session: Magnetic Thin Films and Surfaces
Presenter: G. Witte, Ruhr-University Bochum, Germany
Authors: G. Witte, Ruhr-University Bochum, Germany
L. Ruppel, Ruhr-University Bochum, Germany
Ch. Woell, Ruhr-University Bochum, Germany
S.F. Fischer, Ruhr-University Bochum, Germany
U. Kunze, Ruhr-University Bochum, Germany
T. Last, Ruhr-University Bochum, Germany
Correspondent: Click to Email
On account of its large spin transfer length (i.e. Rashba effect) InAs constitutes a promising material for future spintronic applications. Of particular interest in this context are details of the growth and properties of thin ferromagnetic films on this substrate. Here we report on a combined LEED, XPS and SQUID study of epitaxially grown Fe-films on the indium rich InAs(100)-c(8x2)/(4x2) surface with a particular emphasize on interface alloying and its influence on the magnetic properties. While deposition at room temperature leads to the appearance of a distinct (1x1) LEED pattern for films thicker than 2nm indicating an epitaxial growth of Fe(100) films, the corresponding XPS data reveal the presence of an iron-arsenide species which floates at the surface upon further film growth. Postdeposition annealing causes no improvement of the film quality but enhances the amount of arsenic at the surface. Surprisingly, rapid flash annealing of the films above 700K leads, however, to a thermal dissociation and desorption of the surface arsenic which is accompanied by a change of the film morphology and formation of disconnected islands. This suggests that the epitaxial growth of Fe films on InAs(100) is stabilized by the surface arsenide via a "surfactant effect". Corresponding ex-situ SQUID measurements for 10nm Fe films capped by a 20nm Ag film revealed bulk like magnetic properties over a temperature range of 5-300K. In contrast to that thin Ag films of only 1nm are not sufficient to prevent a partial oxidation of the Fe films as inferred from the XPS data and lead to the appearance of a pronounced exchange bias effect at low temperatures. This observation stress the importance of an appropriate capping.