SURFACE MAGNETISM OF ULTRATHIN GAMMA-FE FILMS INVESTIGATED BY NONLINEAR MAGNETOOPTICAL KERR-EFFECT

By magnetization induced second harmonic generation (MSHG) the surface magnetization of fee Fe films on Cu(100) is studied. The tetragonally distorted phase below 4 monolayers (ML) and the relaxed fee phase abo ve 4 ML can unambigously be distinguished by different average MSHG si gnals. Nearly constant asymmetry of the second harmonic intensities be tween 1.3 and 10 ML proves, to a good approximation, thickness indepen dence of the surface magnetization irrespective of the phase transitio n at 4 ML. The nonlinear Kerr angle amounts to 4 degrees.