Magnetism in Ge by ion implantation with Fe and Mn

Previously, ferromagnetic layers of Ge were produced by co-doping with Mn and Fe. While these layers were prepared by molecular beam epitaxy in the present study ion implantation is used for preparation. Implantation conditions were chosen that a maximum doping concentration of 6 atomic % per dopant was achieved. One sample set was implanted at 260 °C, another one at room temperature. Samples were characterized by conversion electron Mössbauer spectroscopy, Auger electron spectroscopy, superconducting quantum interference device magnetometry, transmission electron microscopy, and Rutherford backscattering spectroscopy. Several samples were recovered by flash lamp annealing. Ferromagnetism in Ge may be induced, however, in all cases the origin of the magnetism was not intrinsic but from secondary phases. Such phases were already formed due to implantation at elevated temperature. Implantation at room temperature prevents the formation but let the samples remain non-ferromagnetic. Subsequent short time annealing above a special limit will produce secondary phases or metal rich regions and ferromagnetism, annealing below does not change the magnetic behaviour but let diffusion processes start. Although nearly identical concentration conditions like in the study first mentioned were adjusted the nature of the magnetism is another one. It is hint that the order/disorder state of the magnetic atoms containing layer plays the more important role.