Structural and magnetic properties of Mn5Ge3 clusters in a dilute magnetic germanium matrix

We have characterized the structural and magnetic properties of low-temperature molecular-beam epitaxy grown Ge:Mn by means of high-resolution transmission electron microscopy (HR-TEM), energy dispersive x-ray spectroscopy, and superconducting quantum interference device (SQUID) magnetometry. We find a coherent incorporation of Mn5Ge3 clusters in an epitaxially grown Ge:Mn matrix, which shows the characteristics of a diluted magnetic semiconductor phase of Mn-doped Ge. The clusters are preferentially oriented with the hexagonal [0001] direction parallel to the [001] growth direction of the Ge:Mn matrix, as determined from both HR-TEM and SQUID measurements. (c) 2006 American Institute of Physics.