The effects of interstitial oxygen on superconducting electronic phases in strontium and oxygen co-doped La1.937Sr0.063CuO4+$\delta$
Shen Cai-Xia(申彩霞), Shen Xiao-Li(慎晓丽), Lu Wei(陆伟), Dong Xiao-Li(董晓莉), Li Zheng-Cai(李正才), Xiong Ji-Wu(熊季午), and Zhou Fang(周放)†
National Laboratory for Superconductivity, Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China
Abstract Strontium and oxygen co-doped La$_{1.937}$Sr$_{0.063}$CuO$_{4 + \delta }$ superconductor with $T_{\rm c}\approx 40$ K, which is obtained by oxidizing strontium-doped starting ceramic sample La$_{1.937}$Sr$_{0.063}$CuO$_{4}$ in NaClO solution, is annealed under different conditions to allow interstitial oxygen to redistribute. The evolution of the intrinsic superconducting property with the oxygen redistribution is studied in detail by magnetic measurements in various fields. It is found that there occurs the electronic phase separation from the single superconducting phase with $T_{\rm c} \approx40$ K into two coexisting superconducting states with values of $T_{\rm c}$: 15 and 40 K or of 15 and 35 K in this system, depending on annealing condition. Our results indicate that the 15, 35 and 40 K superconducting phases associated with the excess oxygen redistribution are all thermodynamically meta-stable intrinsic states in this Sr/O co-doped cuprate.
Received: 25 February 2008
Revised: 04 March 2008
Accepted manuscript online:
PACS:
74.62.Dh
(Effects of crystal defects, doping and substitution)
(Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization)
Fund: Project supported by the State Key
Development Program for Basic Research of China (Grant No
2006CB0L0302), the National Natural Science Foundation of China
(Grant No 10574149) the work is also partially supported by European
Union project CoMePhS.
Cite this article:
Shen Cai-Xia(申彩霞), Shen Xiao-Li(慎晓丽), Lu Wei(陆伟), Dong Xiao-Li(董晓莉), Li Zheng-Cai(李正才), Xiong Ji-Wu(熊季午), and Zhou Fang(周放) The effects of interstitial oxygen on superconducting electronic phases in strontium and oxygen co-doped La1.937Sr0.063CuO4+$\delta$ 2008 Chin. Phys. B 17 2712
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