Carrier-induced ferromagnetism in Ge(Mn,Fe) magnetic semiconductor thin-film structures

摘要

We report on the carrier-induced ferromagnetism in Ge(Mn,Fe) magnetic semiconductor insulating-type thin-film structures prepared using sequential deposition at T_g=520 K with subsequent annealing at T_g. In the resulting films Mn and Fe are diffused in the Ge matrix without compromising the epitaxial structure. The anomalous Hall effect serves as a manifestation of the carrier-induced magnetism, with p-type conductivity and the Curie temperature T_C=209 K. The additional doping with Fe stabilizes epitaxial growth and carrier-mediated magnetism at levels of magnetic doping exceeding 10%. We conclude that indirect ferromagnetic exchange is mediated by localized holes with concentration n～10~(20) cm~(-3) and mobility μ～ 10 cm~2/(V s).