A study was made of the Mn local structure, magnetism, and Ga moments in molecular beam epitaxially grown Mn-doped GaN films. Using X-ray absorption spectroscopy and magnetic circular dichroism, 2 distinct Mn sites and a Ga moment anti-parallel to Mn were found. First-principles calculations reproduced these results and indicated that Mn preferentially populated Ga sites neighboring N split interstitial defects. These results showed that defects could strongly affect Mn ordering and magnetism, and that the GaN valence band was polarized; providing a long-range ferromagnetic ordering mechanism for Ga1-xMnxN.

Role of Defect Sites and Ga Polarization in the Magnetism of Mn-Doped GaN. D.J.Keavney, S.H.Cheung, S.T.King, M.Weinert, L.Li: Physical Review Letters, 2005, 95[25], 257201 (3pp)