Nanosized superparamagnetic precipitates in cobalt-doped ZnO M. Opel, K.-W. Nielsen, S. Bauer, S. T.B. Goennenwein, J. C. Cezar, D. Schmeisser, J. Simon, W. Mader and R. Gross Eur. Phys. J. B, 63 4 (2008) 437-444 Published online: 03 July 2008 DOI: 10.1140/epjb/e2008-00252-4