Ferromagnetism of MnO and Mn3O4 nanowires

The MnO and Mn3O4 nanowires were grown by thermal evaporation of MnCl2 under the Ar flow. The diameter is in the range 50-100 nm and the length is about 20 ?m. The MnO and Mn3O4 nanowires consist of single-crystalline cubic MnO and tetragonal Mn3O4 crystals, respectively, grown uniformly with the [100] direction. The XPS data suggest that the majority of nanowires could be MnO nanowires. The temperature-dependent FC and ZFC magnetization curves with H=0.1-30 kOe, and the hysteresis curves measured at 5-300 K provide an evidence for the ferromagnetism with TC = 12 K and 43 K, for the MnO and Mn3O4 nanowires, respectively. The hysteresis curves at low temperatures were resolved well by two ferromagnetic components based on Brillouin function form, confirming the ferromagnetism of both MnO and Mn3O4 nanowires. We conclude that the single- crystalline MnO and Mn3O4 nanowires could be excellent ferromagnetic nanomaterials.