The magnetic properties related to cation vacancies in GaN are investigated by first-principles calculations. The results show that a neutral Ga-vacancy induces 3μB magnetic moment in GaN, but is difficult to form due to the high formation energy. It is found that the Ga-vacancy formation energy can be reduced by adding electrons with uniform compensating positive background charge, by nano-structure engineering, or by co-doping donor-like defects. The Ga-vacancy induced colossal magnetic moment in Gd-doped GaN can be modulated by co-doping th...
