In this work, we analyse the influence of C4+ irradiation with ion flounce of 3×10 12 up to 2.3×10 15 ion•cm−2 on significant enhancement of the critical current density, Jc, in BaFe1.9Ni0.1As2 single crystals. Jc was increased from 0.61×105 up to 0.94×105 A/cm2 at T=10 K and H=0.5 T. BaFe1.9Ni0.1As2 single crystals with and without the C4+-irradiation were characterized by magneto-transport and magnetic measurements up to 13 T over a wide range of temperatures below and above the superconducting critical temperature, Tc. It is found that the C4+-irradiation causes little change in Tc, but it can greatly enhance the in-field critical current density by a factor of up to 1.5. Higher dose of C4+ions, causes further Jc enhancement at T=10 K. furthermore, flux jumping completely disappeared at T=2 K after second C4+-irradiation. Our Monte Carlo simulation results show that all the C4+ions end up in a well defined layer, causing extended defects and vacancies at the layer, but few defects elsewhere on the irradiation paths. Furthermore, the normal state resistivity is enhanced by the light C4+-irradiation, while the upper critical field, Hc2 , the irreversibility field, Hirr, and Tc were affected very little.

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