Magnetic domains in epitaxial Fe/GaAs micro-patterned wires

The magnetic domain evolution during the magnetization reversal in in-plane magnetized epitaxial Fe/GaAs(001) wire elements with dimensions of 15 mu m width X 500 mu m length X 300 Angstrom thickness has been studied using a scanning Kerr microscope. The two jump switching processes, characteristic of the magnetization reversal in continuous epitaxial Fe(001) films with four-fold in-plane anisotropy, are observed. However, the domain nucleation and growth processes which mediate the discontinuous and irreversible magnetization switching at the two critical reverse fields H-c1 and H-c2 are different from those in the continuous film. They are found to be determined by the orientation of the applied field with respect to the short and the long wire axis and hence are ''shape''-anisotropic. This shape-anisotropy is a combined local dipolar field and anisotropic finite size effect, allowing the growth of domains only from the long/short wire axis and the propagation of domains only in direction of the short/long wire axis respectively according to the applied field direction. (C) 1997 American Institute of Physics.