Superconductivity induced by oxygen deficiency in La(0.85)Sr(0.15)FeAsO(1-delta)

作者：Wu G; Chen H; Xie Y L; Yan Y J; Wu T; Liu R H; Wang X F; Fang D F; Ying J J; Chen X H^*

来源：Physical Review B, 2008, 78(9): 092503.

DOI：10.1103/PhysRevB.78.092503

We synthesized single phase La(0.85)Sr(0.15)FeAsO(1-delta) samples and systematically studied the effect of oxygen deficiency in this system. It is found that partial substitution of Sr for La induces the hole carrier evidenced by positive thermoelectric power (TEP) but no bulk superconductivity is observed. The superconductivity can be realized by annealing the as-grown sample in vacuum to produce the oxygen deficiency. With increasing oxygen deficiency, the superconducting transition temperature (T(c)) increases and the maximum T(c) reaches 26 K - the same as that observed in the LaFeAsO(1-x)F(x) system. TEP changes the sign from positive for the nonsuperconducting as-grown sample to negative for the superconducting samples with oxygen deficiency, while RH keeps negative for all samples. It suggests that the dominated carrier in La(0.85)Sr(0.15)FeAsO(1-delta) is electronlike.

• 出版日期2008-9
• 单位中国科学技术大学