Domain wall creep in (Ga,Mn)As

We have compared the scaling exponents in scaling formula for magnetic domain wall creep by measuring the magnetic-field induced domain wall velocity of (Ga,Mn)As layers grown on (In,Al)As semistep-graded buffer layer and (In,Ga)As buffer layer. The different critical exponents for the two (Ga,Mn)As layers indicate that the observed creep motions belong to different universality classes, which are found to be governed by the degree of surface roughness due to crosshatch dislocation introduced during epitaxial growth. Domain wall creep motion in (Ga,Mn)As layer grown on (In,Al)As with flatter surface belongs to random-field disorder, whereas that in (In,Ga)As to random-bond disorder. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3467048]