Suppression of the critical temperature of superconducting NdFeAs(OF) single crystals by Kondo-like defect sites induced by α-particle irradiation C. Tarantini 1 , M. Putti 3 , A. Gurevich 1 , Y. Shen 2 , R.K. Singh 2 , J.M. Rowell 2 , N. Newman 2 , D.C. Larbalestier 1 , Peng Cheng 4 , Ying Jia 4 , Hai-Hu Wen 4 1 National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, USA 2 Department of Materials Science and Engineering, Arizona State University, Tempe, AZ, USA 3 CNR-INFM-LAMIA and Department of Physics, University of Genova, Genova, Italy 4 Institute of Physics and National Laboratory of Condensed Matter Physics, Chinese Academy of Sciences, Beijing, China Abstract We report a comprehensive investigation of the suppression of the critical temperature T c of NdFeAs(OF) single crystal by α-particle irradiation. Our data indicate that irradiation defects produce both nonmagnetic and magnetic scattering, resulting in the Kondo-like excess resistance Δρ(T) ∝ lnT over 2 decades in temperatures above T c . Despite high densities of irradiation defects, the dose at which T c is suppressed to zero is comparable to that for MgB 2 but is well above the corresponding values for cuprates. PACS: 74.25.Fy, 61.80.Jh, 74.62.Dh.