Magnetic and transport properties of Ge: Mn granular system

Ge:Mn granular thin films were fabricated on semi-insulating GaAs(001) substrates by molecular beam epitaxy. Transmission electron microscopy and Raman study showed that the sample has a granular structure consisting of GeMn crystallites in a Ge polycrystalline host matrix. A Curie temperature of similar to 300 K was observed in the magnetization measurement, suggesting that the granules are Mn5Ge3. The granular nature of the material was also revealed clearly in the differential conductance vs. bias voltage curves. The unique conductance versus bias voltage curve suggests that the electrical transport is determined by Schottky barriers at the nanoparticle/host matrix interface. This type of material might be useful for studying spin-injections from metallic magnetic nanostructures to semiconductors. (c) 2005 Elsevier B.V. All rights reserved.