The effects of interstitial oxygen on superconducting electronic phases in strontium and oxygen co-doped La1.937Sr0.063CuO4＋δ

Strontium and oxygen co-doped La1.937Sr0.063CuO4＋δ superconductor with Tc≈ 40K, which is obtained by oxidizing strontium-doped starting ceramic sample La1.937Sr0.063CuO4 in NaC10 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 Tc ≈ 40 K into two coexisting superconducting states with values of Tc： 15 and 40K 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.

The effects of interstitial oxygen on superconducting electronic phases in strontium and oxygen co-doped La1.937Sr0.063CuO4+δ

Strontium and oxygen co-doped LaLaLa$_{2 - x}$Sr$_{x}$CuO$_{4}$,intrinsic electronic phase, interstitial oxygenProject supported by the State KeyDevelopment Program for Basic Research of China (Grant No2006CB0L0302), the National Natural Science Foundation of China(Grant No 10574149) the work is also partially supported by EuropeanUnion project CoMePhS.7430C, 7470S3/4/2008 12:00:00 AMStrontium and oxygen co-doped La$_{1.937}$Sr$_{0.063}$CuO$_{4 +delta }$ superconductor with $T_{rm c}approx 40$,K, which isobtained by oxidizing strontium-doped starting ceramic sampleLa$_{1.937}$Sr$_{0.063}$CuO$_{4}$ in NaClO solution, is annealedunder different conditions to allow interstitial oxygen toredistribute. The evolution of the intrinsic superconductingproperty with the oxygen redistribution is studied in detail bymagnetic measurements in various fields. It is found that thereoccurs the electronic phase separation from the singlesuperconducting phase with $T_{rm c} approx40$,K into twocoexisting superconducting states with values of $T_{rm c}$: 15 and40,K or of 15 and 35,K in this system, depending on annealingcondition. Our results indicate that the 15, 35 and 40,Ksuperconducting phases associated with the excess oxygenredistribution are all thermodynamically meta-stable intrinsicstates in this Sr/O co-doped cuprate.