Properties of Ferromagnetic Ga1-xMnxN Films Grown by Ammonia-MBE
  Using ammonia as nitrogen source for molecular beam epitaxy, the GaN-based diluted magnetic semiconductor Ga1-xMnxN is successfully grown with Mn concentration up to x~6.8% and with p-type conductivity. The films have wurtzite structure with substitutional Mn on Ga site in GaN. Magnetization measurements revealed that Ga1-xMnxN is ferromagnetic at temperatures higher than room temperature. The ferromagnetic-paramagnetic transition temperature, Tc, depends on the Mn concentration of the film. At low temperatures, the magnetization increases with increasing of magnetic field, implying that a paramagnetic-like phase coexists with ferromagnetic one. Possible explanations will be proposed for the coexistence of two magnetic phases in the grown films. 
Saki Sonoda, Hidenobu Hori, Yoshiyuki Yamamoto, Takahiko Sasaki,   Masugu Sato, Saburo Shimizu, Ken-ichi Suga and Koichi Kindo