Metal-semiconductor transition and magnetic properties of epitaxially grown MnAs/GaAs superlattices

We successfully grew epitaxial MnAs/GaAs superlattices at various growth temperatures (T(g)) with a periodicity of 5/5 nm using molecular-beam epitaxy and characterized their magnetic and electrical transport properties. Structural analysis shows that the magnetic anisotropy originates from the crystal domain structure of the MnAs layers. The metallic behavior for the sample with T(g)=375 degrees C systematically changed to semiconducting on increasing T(g) up to 540 degrees C. The transport properties of thin single layered MnAs films with a thickness of 20 nm showed the same T(g) dependency. These observations indicate that the semiconducting characteristics of MnAs/GaAs superlattices are attributable to a radical alteration of the electronic structure of the MnAs layers. (C) 2008 American Institute of Physics.