The micromagnetic properties of MnAs thin films grown on the (111)B-oriented GaAs surface have been investigated. Compared to films grown on (001) surfaces, these films exhibit completely different domain patterns, as the c axis of the hexagonal unit cell is oriented normal to the surface. In the course of the first order phase transition, ferromagnetic alpha-MnAs forms a network of quasihexagonal areas separated by beta-MnAs. We present an analysis of the micromagnetic properties based on imaging and simulations. We observe closure domains that either appear as a vortex-like state or a stripe structure. (c) 2006 American Institute of Physics.