中国物理B ›› 2008, Vol. 17 ›› Issue (7): 2712-2716.doi: 10.1088/1674-1056/17/7/059
申彩霞, 慎晓丽, 陆伟, 董晓莉, 李正才, 熊季午, 周放
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)†
摘要: 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.
中图分类号: (Effects of crystal defects, doping and substitution)