Relevant characteristics of undoped GaMnN grown by using molecular beam epitaxy

GaN:Mn epilayers were grown on Al2O3 substrate by using molecular beam epitaxy (MBE). Xray diffraction (XRD) data showed intrinsic GaMnN and precipitates including MnGa and MnN. PL transitions (e, Mn) and (D, Mn) related to Mn were remarkably activated. Clear ferromagnetic hysteresis loops were obtained in both samples, which means a good formation of ferromagnetic coupling. The M-T curves revealed a curie temperature (T_c) of 140 ~ 170 K which is intrinsic to GaMnN and a Tc of above 300 K which is due to the MnGa and the MnN precipitates. The samples clearly displayed a magnetic resonance at a field of around 200 - 400 mT. Electron spin resonance (ESR) data showed that the shift of (H_center) (i.e., H_center = 337 - H_center [mT]) were greater than 20 mT for samples, and the appearance of a Hcenter with a positive H_center is indicative of the samples having obvious ferromagnetism. The incorporated Mn ions are in a 2+ ionic state (i.e., Mn²⁺) because Mn2+ with a spin state of S = 5/2 typically exhibits a magnetic resonance with g ≈ 2 when Mn is doped into semiconductors.