LORENTZ ELECTRON-MICROSCOPY STUDIES OF MAGNETIZATION REVERSAL PROCESSES IN EPITAXIAL FE(001) FILMS

The magnetic domain structure and microscopic magnetization reversal p rocesses in epitaxial Fe/GaAs(001) films with cubic anisotropy and in- plane easy axes have been investigated by a Lorentz microscope equippe d with a magnetizing stage. For the films of a few hundred angstroms t hickness we observe the single domain remanent state predicted for a t wo-dimensional film but find that domains play a crucial role in the m agnetic reversal process. For reversal along the in-plane [110] direct ions (hard axes), magnetization reversal proceeds via a combination of coherent rotation and displacements of weakly pinned 90 degrees domai n walls at critical fields. For magnetization reversal along the in-pl ane [100] directions (easy axes), an irregular checkerboard domain str ucture develops at the critical field and both 180 degrees and 90 degr ees domain walls coexist. The reversal of the domains with magnetizati on vector opposite to the applied field direction takes place by a com bination of two 90 degrees reorientations. We discuss how these proces ses are related to the magnetic anisotropies present in the film and t he macroscopic M-H hysteresis curves.