A comparative study on magnetic and magnetotransport properties in (Ga, Mn)N epitaxial films grown on undoped and n-type GaN by PEMBE

We present a comparative study on the magnetic and magnetotransport properties of (Ga, Mn)N epitaxial films grown on undoped GaN and n-type GaN templates by plasma-enhanced molecular beam epitaxy. Regardless of the kind of substrate, the (Ga, Mn)N epitaxial films were found to obviously exhibit ferromagnetic ordering with a Curie temperature exceeding room temperature. However, the negative magnetoresistances of the (Ga, Mn)N films grown on undoped GaN and n-type GaN templates show a remarkable difference. Negative magnetoresistance for the (Ga, Mn)N films grown on undoped GaN templates was observed up to room temperature, while negative magnetoresistance for the (Ga, Mn)N grown on n-type GaN templates was observed only below 100 K. Considering that the Mn concentrations in the (Ga, Mn)N films are the same, it is believed that the content of Mn spins in the (Ga, Mn)N films grown on n-type GaN templates is not sufficient to order all the carriers in the n-type GaN and the film itself, since the Mn spins in (Ga, Mn)N interact with the carriers in both.