Study of the room-temperature ferromagnetic GaMnN thin films

•The properties of the samples strongly depended on the substrate temperature.•All the samples were confirmed to be ferromagnetic at room temperature.•Mn3+ ions play an important role in the origin of the ferromagnetism.•The room-temperature ferromagnetism can be explained by the BMP theory.

Room-temperature ferromagnetic GaMnN thin films were obtained on sapphire (0001) substrate at different temperatures by using laser assisted molecular beam epitaxy. It is found that the structural, morphological and magnetic properties are strongly dependent on the substrate temperature. At room temperature, all the samples show ferromagnetic behavior, which can be explained by the bound magnetic polaron theory. The Mn3+ ions play an important role in the origin of the room temperature ferromagnetism. The saturated magnetization could be weakened by the donor-like nitrogen vacancies. It is found that the optimal substrate temperature is 750 °C in our experiments.