Structural and magnetic characterization of Ge_0.99Mn _0.01 nanowire arrays

A supercritical fluid inclusion-phase technique has been developed to embed Ge_0.99Mn_0.01 nanowires, with size-monodisperse diameters, within the pores of anodized aluminum oxide hosts. This article describes the synthesis and structural and magnetic characterization of these nanocomposite materials. The experimental results indicate the presence of both para- and ferromagnetic phases in Ge_0.99Mn_0.01 nanowires. Paramagnetism could be related to individual Mn atoms in the nanowire core. The ferromagnetic phase yields a high Curie temperature, T_c > 300 K, which is surprisingly high for this class of materials. Extended X-ray atomic fine structure (EXAFS) analysis confirmed that the ferromagnetism observed originates from the manganese atoms located at the nanowire-membrane interface.