  Wurtzite (Ga,Mn)N films showing ferromagnetic behaviour at room temperature
were successfully grown on sapphire(0001) substrates by molecular beam epitaxy
using ammonia as nitrogen source. Magnetization measurements were carried out
by a superconducting quantum interference device at the temperatures between
1.8K and 300K with magnetic field applied parallel to the film plane up to 7T.
The magnetic-field dependence of magnetization of a (Ga,Mn)N film at 300K were
ferromagnetic, while a GaN film showed Pauli paramagnetism like behaviour. The
Curie temperatures of a (Ga,Mn)N film was estimated as 940K.
