Atomic scale morphology of self-organized periodic elastic domains in epitaxial ferromagnetic MnAs films

The surface of epitaxial MnAs layers grown on GaAs(001) substrates by molecular beam epitaxy is studied by atomic force microscopy and scanning tunneling microscopy (STM). A periodic array of alternating ridges and grooves is observed. The periodicity ranges from 200 to 900 nm and increases with increasing layer thickness. The terrace-step morphology and the surface reconstruction on the ridges and in the grooves are imaged by STM. It is found that both are independent from the ridge-groove structure, supporting the idea that the formation of the ridge-groove structure is due to elastic distortion of the film during cooling after growth.