Surface modification for epitaxial growth of single crystalline cobalt thin films with uniaxial magnetic anisotropy on GaN(0001)-1 x 1 surfaces

Epitaxial growth and magnetic properties of Co thin films on GaN(0001)-1 x 1 surfaces are studied. The films show degraded saturation magnetization due to the interfacial interaction. On excess-Ga-induced pseudo-1 x 1 surface, 30 degrees -rotation domains in the Co epilayer are inevitable and the films show in-plane magnetic anisotropy. By annealing the starting surface of pseudo-1 x 1 and to achieve a Ga-less 1 x 1 surface, single domain Co epifilms having orientations aligned with the substrate can be grown, which facilitates in-plane uniaxial magnetic anisotropy.