Microscopic magnetic relaxation processes in epitaxial Fe/GaAs(0 0 1) mesostructures

The magnetic relaxation and domain processes in epitaxial Fe/GaAs(0 0 1) thin films and square dots have been investigated using time-resolved scanning Kerr microscopy. For 55 and 250 Å Fe/GaAs(0 0 1) continuous films, it is clearly seen that relaxation proceeds by both discontinuous and single ‘jumps’. Magnetic relaxation studies reveal that large and abrupt wall displacements occur for the magnetisation reversal in 300 Å epitaxial Fe/GaAs(0 0 1) square dots, regardless of dot size ( w= 5–45 μm ). Domain observations demonstrate that domain wall motion dominates the magnetisation reversal in the dot structures in spite of the presence of the dot edges.