Ferromagnetism of 3d-impurities substituted in Ge

Abstract We have studied the electronic and magnetic properties of germanium doped with 3d-impurities (V–Ni) using first-principles band structure method. It is found that the ferromagnetic (FM) spin configuration is more energetically favorable than the antiferromagnetic (AFM) state for Mn-, Fe-, Co- and Ni-doped Ge, whereas the situation is reversed for V- and Cr-doped systems. The calculated electronic and magnetic structures of Mn-, Fe-, Co- and Ni-doped Ge show that half metallicity is obtained only for Mn-doped Ge that consistent with the integer value for the total magnetic moment, while Fe-, Co-, Ni-doped ones are metallic. Furthermore, the FM coupling between the Mn d states and the anion dangling-bond p states is believed to responsible for the stabilization of the FM order in Mn-doped Ge.