Comparison of the magnetic properties of GeMn thin films through Mn L -edge x-ray absorption

Abstract

X-ray absorption spectroscopy of epitaxial GeMn thin films reveals an experimentally indistinguishable electronic configuration of Mn atoms incorporated in Ge1-x Mnx nanoclusters and in precipitates of the intermetallic compound Mn5 Ge3, respectively. However, the average magnetic response of thin films containing Ge1-x Mnx nanoclusters is lower than the response of films containing Mn5 Ge3 precipitates. This reduced magnetic response of Ge1-x Mnx nanoclusters is explained in terms of a fraction of Mn atoms being magnetically inactive due to antiferromagnetic coupling or the presence of structural disorder. A determination of the role of magnetically inactive Mn atoms in the self-assembly of the thermodynamically metastable Ge1-x Mnx nanoclusters seems to be an essential ingredient for an enhanced control of this promising high Curie temperature magnetic semiconductor. © 2009 American Institute of Physics.