Surface superconductivity on SrFe2As2 single crystals induced by ion implantation S. V. Chong, J. L. Tallon, F. Fang, J. Kennedy, K. Kadowaki and G. V. M. Williams EPL, 94 3 (2011) 37009 Published online: 28 April 2011 DOI: 10.1209/0295-5075/94/37009