Ferromagnetism in Mn and Cr doped GaN by thermal diffusion

Doping of magnetic element Mn and Cr in GaN was achieved by thermal diffusion. The conductivity of the samples, which were all n-type, did not change significantly after the diffusion doping. X-ray diffraction measurements revealed no secondary phase in the samples. Experiments using superconducting quantum interference device (SQUID) showed that the samples were ferromagnetic at 5 and 300 K, implying the Curie temperature to be around or over 300 K, despite their n-type conductivity.