Magnetism depending on carrier in (Zn,Co)O H.-J. Lee, H.-H. Nam, Y.-C. Cho, S.-K. Kim, C. H. Park, C. R. Cho and S.-Y. Jeong EPL, 78 1 (2007) 17001 Published online: 09 March 2007 DOI: 10.1209/0295-5075/78/17001