Significant enhancement of superconducting properties in the FeSe0.5Te0.5 bulks by minor Sn addition.

Sn addition improves bulk superconducting properties of FeSe 0.5 Te 0.5 with the increase of onset transition temperature and sharpens the transition width. The critical current density ( J c ) of Sn-added sample is about 7×10 3 A cm −2 in self field and maintains a stable value of 3×10 2 A cm −2 even beyond 60,000 Oe at 4.3 K, much higher than that of the Sn-free one. Phase compositions and morphology characterizations indicate that minor Sn addition facilitates the formation of the superconducting phase whose composition is closer to the ideal one, and suppresses the formation of Fe 7 Se 8 impurity and amorphous phase, which contribute to the improvement of J c . [ABSTRACT FROM AUTHOR]