Strain-mediated phase coexistence in MnAs heteroepitaxial films on GaAs: An x-ray diffraction study

The temperature-dependent phase coexistence between crystalline phases in heteroepitaxial films of MnAs on GaAs is studied. The epitaxial constraints on the film expansion are analyzed. The x-ray-diffraction data are fitted to a model of periodic elastic domains. The temperature dependencies of phase fractions, the domain sizes, and the misfits are simultaneously obtained. The domain sizes correspond to the minimum of elastic energy, which proves the equilibrium state of the heteroepitaxial system at each temperature.