Effect of carbon doping on magnetic flux pinning and superconducting performance in FeSe0.5Te0.5 single crystals

Abstract A series of carbon-doped single crystals with nominal composition FeSe 0.5 Te 0.5 were synthesized by a self-flux method. X-ray diffraction indicated that the lattice parameter c increases with increasing carbon content, suggesting that carbon atoms enter the lattice. The critical current densities were measured and the flux pinning mechanism and its change with doping were analyzed. These samples showed a higher J c in high magnetic fields as well as a narrower superconducting transition. We studied the impact of the introduction of carbon into FeSe 0.5 Te 0.5 on the temperature dependence of the irreversibility field H irr ( T ) and upper critical field ( H c2 ). The pinning mechanism for the system was obtained via analysis of J c .