Mn0.06Ge0.94diluted magnetic semiconductor epitaxially grown on Ge(001): Influence ofMn5Ge3nanoscopic clusters on the electronic and magnetic properties

Abstract

The structural, electronic, and magnetic properties of the ${\mathrm{Mn}}_{0.06}{\mathrm{Ge}}_{0.94}$ diluted magnetic semiconductor, grown at $520\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ by molecular-beam epitaxy on $\mathrm{Ge}(001)2\ifmmode\times\else\texttimes\fi{}1$, have been investigated. Diluted and highly ordered alloys, containing ${\mathrm{Mn}}_{5}{\mathrm{Ge}}_{3}$ nanocrystals, were grown. The valence band photoelectron spectrum of ${\mathrm{Mn}}_{0.06}{\mathrm{Ge}}_{0.94}$ shows a feature located at $\ensuremath{-}4.2\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ 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 ${\mathrm{Mn}}_{5}{\mathrm{Ge}}_{3}$ nanocrystallites. The Mn ${L}_{2,3}$ x-ray absorption spectrum of this polyphase film shows no marked multiplet structure, but a bandlike character.