Evidence for Carrier-Induced High-Tc Ferromagnetism in Mn-doped GaN film
  A GaN film doped with 8.2 % Mn was grown by the molecular-beam-epitaxy technique. Magnetization measurements show that this highly Mn-doped GaN film exhibits ferromagnetism above room temperature. It is also revealed that the high-temperature ferromagnetic state is significantly suppressed below 10 K, accompanied by an increase of the electrical resistivity with decreasing temperature. This observation clearly demonstrates a close relation between the ferromagnetism with extremely high-Tc and the carrier transport in the Mn-doped GaN film. 
S. Yoshii, S. Sonoda, T. Yamamoto, T. Kashiwagi, M. Hagiwara, Y.   Yamamoto, Y. Akasaka, K. Kindo, H. Hori