Control and properties of magnetic nanostructures in nitride semiconductors

We review [1] studies of MOVPE (Ga,Fe)N [2-7] and (Ga,Mn)N [8,9], combining magnetic [2-4,6,8,9], magnetooptical [3], and XANES [4,5,8] investigations with a comprehensive structural and chemical characterization by SIMS, TEM, EDS [2,4,6,8,9], synchrotron-XRD [4,6,8], EXAFS [5,8], and PEEM [7]. We show that the Fe ions aggregate into Fe$_{x}$N nanocrystals either by crystallographic or by chemical phase separation, controlled by the growth conditions and by co-doping. Depending on the degree of nitridation, these nanocrystals are either ferromagnetic or antiferromagnetic. \\[4pt] [1] A. Bonanni and T. Dietl, Chem. Soc. Rev. 39, 528 (2010);\\[0pt] [2] A. Bonanni et al., Phys. Rev. B 75, 125210 (2007);\\[0pt] [3] W. Pacuski et al., Phys. Rev. Lett. 100, 037204 (2008);\\[0pt] [4] A. Bonanni et al., Phys. Rev. Lett. 101, 135502 (2008);\\[0pt] [5] M. Rovezzi et al., Phys. Rev. B 79, 195209 (2009);\\[0pt] [6] A. Navarro-Quezada et al., Phys. Rev. B 81, 205206 (2010);\\[0pt] [7] I. Kowalik et al., arXiv:1011.0847;\\[0pt] [8] W. Stefanowicz et al., Phys. Rev. B 81, 235210 (2010);\\[0pt] [9] A. Bonanni et al. arXiv~: 1008.2083.