MAGNETISM AND GROWTH IN PSEUDOMORPHIC FE FILMS ON W(100)

Magnetism and growth of pseudomorphic Fe(100) films grown on a W(100) substrate have been investigated using spin polarized low energy electron diffraction (SPLEED). Different growth modes of the films at different substrate temperatures T-p can be inferred from the temperature dependence of the magnetic order. The Curie-temperature T-c increases monotonously with coverage theta in the temperature range 120 less than or equal to T-c less than or equal to 350 K for 1.4 less than or equal to theta less than or equal to 2.5 ML, with a tendency to saturation at the completion of the bilayer, for films grown at 300 K and for annealed films. We found a critical temperature T-c = 220 +/- 5 K and critical behavior of the magnetic order for the completed bilayer independent of preparation conditions. The temperature dependence of the exchange asymmetry A(ex)(T) is different for different incident beam parameters at temperatures well below T-c. In the vicinity of T-c, A(ex)(T) follows a power law for films theta less than or equal to 2 ML, A(ex)(T) similar to (T-c - T)(beta'), with an effective exponent beta' = 0.22 +/- 0.01 independent of theta.