Magnetic Mn(5)Ge(3) nanocrystals embedded in crystalline Ge: a magnet/semiconductor hybrid synthesized by ion implantation

The integration of ferromagnetic Mn(5)Ge(3) with the Ge matrix is promising for spin injection in a silicon-compatible geometry. In this paper, we report the preparation of magnetic Mn(5)Ge(3) nanocrystals embedded inside the Ge matrix by Mn ion implantation at elevated temperature. By X-ray diffraction and transmission electron microscopy, we observe crystalline Mn(5)Ge(3) with variable size depending on the Mn ion fluence. The electronic structure of Mn in Mn(5)Ge(3) nanocrystals is a 3d(6) configuration, which is the same as that in bulk Mn(5)Ge(3). A large positive magnetoresistance has been observed at low temperatures. It can be explained by the conductivity inhomogeneity in the magnetic/semiconductor hybrid system.