We have studied the influence of intrinsic and extrinsic defects in the magnetic and electrical transport properties of Co-doped ZnO thin films. X ray absorption measurements show that Co substitute Zn in the ZnO structure and it is in the 2+ oxidation state. Magnetization (M) measurements show that doped samples are mainly paramagnetic. From M vs. H loops measured at 5 K we found that the values of the orbital L and spin S numbers are between 1 and 1.3 for L and S = 3/2, in agreement with the representative values for isolated Co 2+. The obtained negative values of the Curie-Weiss temperatures indicate the existence of antiferromagnetic interactions between transition metal atoms.
@article{arxiv.1007.0269,
title = {ZnO:Co Diluted Magnetic Semiconductor or Hybrid Nanostructure for Spintronics?},
author = {F. Golmar and M. Villafuerte and A. Mudarra Navarro and C. E. Rodrıguez Torres and J. Barzola-Quiquia and P. Esquinazi and S. P. Heluani},
journal= {arXiv preprint arXiv:1007.0269},
year = {2016}
}