Possible origins of room-temperature ferromagnetism in GeMn nanowires (NWs) are investigated. Arrays of Ge1-xMnx NWs and Ge/Ge1-xMnx nanocables (NCs) (x=1-5) have been synthesized within the pores of anodized alumina oxide (AAO) membranes. The influence of annealing on the magnetic properties of Ge1-xMnx NWs is studied. The room-temperature ferromagnetism is preserved after the postfabrication annealing in inert atmosphere (T-ann=750 degrees C) demonstrating overall compatibility of Ge1-xMnx NWs with conventional complementary metal-oxide semiconductor technology. The role of oxygen in high-T-C ferromagnetic ordering is investigated in double-phased NCs with a Ge sheath. Despite a barrier to oxygen migration from the AAO membrane, samples still display room-temperature ferromagnetism, hence, ruling out any significant role of oxygen in the explanation of the high T-C in the system. The magnetic properties of the one-dimensional Ge1-xMnx nanostructures can be understood by considering interface related phenomena. (c) 2007 American Institute of Physics.
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