Atomic-scale surface morphology of epitaxial ferromagnetic MnAs thin films grown on vicinal GaAs(111)B substrates

We have investigated the atomic-scale surface morphology and magnetic anisotropy of ferromagnetic MnAs films grown by molecular beam epitaxy on vicinal GaAs(111)B substrates misoriented 2 degrees toward the [(11) over bar2] direction. The MnAs films were grown in a step-flow-like manner and atomically flat terraces appeared on the surface in the temperature range between 220 and 300 degreesC. The terrace width was elongated dramatically in comparison with the original terrace width on the GaAs buffer layer, which resulted from the macrostep formation induced by the step-bunching phenomenon during the growth of MnAs. The terrace width and the macrostep height were 70 and 2 nm, respectively, for the MnAs film grown at 250 degreesC and both values increased with increasing the growth temperature. The MnAs films grown on the vicinal surface were found to exhibit in-plane uniaxial magnetic anisotropy induced by the macrosteps, which was not observed in the MnAs films grown on the exact GaAs(111)B surface. (C) 2001 American Institute of Physics.