Mn0.06Ge0.94 diluted magnetic semiconductor epitaxially grown on Ge(001): Influence of Mn5Ge3 nanoscopic clusters on the electronic and magnetic properties

The structural, electronic, and magnetic properties of the Mn0.06Ge0.94 diluted magnetic semiconductor, grown at 520 K by molecular-beam epitaxy on Ge(001)2x1, have been investigated. Diluted and highly ordered alloys, containing Mn5Ge3 nanocrystals, were grown. The valence band photoelectron spectrum of Mn0.06Ge0.94 shows a feature located at -4.2 eV below the Fermi level, which is the fingerprint of substitutional Mn atoms in the Ge matrix. Magnetization measurements show the presence of a paramagnetic component due to substitutional Mn atoms and of a ferromagneticlike component due to Mn5Ge3 nanocrystallites. The Mn L-2,L-3 x-ray absorption spectrum of this polyphase film shows no marked multiplet structure, but a bandlike character.