Influence of uniaxial anisotropy on the domain pinning fields of ferromagnetic Ga1-xMnxAs films

Abstract

The domain pinning fields of ferromagnetic Ga1-xMnxAs films were investigated using the planar Hall effect (PHE). Two in-plane components of GaMnAs films' anisotropy fields (H-4 parallel to and H-U parallel to), which determine the direction of magnetic easy axes in the (001) plane, were obtained from the PHE's angular dependence fitted with magnetic free energy within the scheme of the Stoner-Wohlfarth model. The domain pinning fields were obtained both with and without consideration of the deviation angle, delta, of magnetic easy axes from the < 100 > crystallographic direction of each sample. The values of domain pinning fields are clearly different between the two methods of analysis and the discrepancy increases with delta. This indicates that the correct direction of the magnetic easy axis (i.e., the influence of uniaxial anisotropy) must be considered to obtain precise values of pinning fields in GaMnAs films. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3486210]