MAGNETOOPTICAL MEASUREMENTS OF MAGNETIZATION REVERSAL IN NANOMETER-SCALE SPUTTERED FE THIN-FILMS

We present a magneto-optical study of the magnetic behavior of sputter ed iron films of various thickness ranging from 2 to 50 nm grown on a silicon substrate. First we calculate the reflection coefficients in t he case of an homogeneous magneto-optical layer with in-plane magnetiz ation. Then we describe a technique in which both in-plane magnetizati on components are detected. Because of the axial deposition procedure, iron films exhibit in-plane uniaxial anisotropy depending on the thic kness of the layer. In particular, we show that, for 4 nm thickness, a nistropy induced by slightly tilted columnar growth can be observed, w hereas for larger thicknesses this in-plane anisotropy vanishes. Using an accurate acquisition system based upon a rapid analog-to-digital c onverter we measured the rapid magnetization reversal. The field sweep rate was varied between 100 Oe/s and 1 MOe/s. We interpret the observ ed dynamical effects in terms of wall movement and microdomain reversa l.