抄録
The role of oxygen in Bi2Sr2CaCu2O8+δ/Ag thick films has been investigated by measuring the coherence lengths and irreversibility lines in two samples with extra oxygen contents of δ=0.17 and δ=0.27. The coherence lengths were estimated by measuring magnetization through the application of a magnetic field both perpendicular and parallel to the c axis. The coherence lengths of the two samples have conformity in the ab plane component, but in the c axis component. the coherence length of the sample with the extra oxygen content of δ=0.27 is 30% larger than that of the sample with the extra oxygen content of δ=0.17. This result led to understanding that the anisotropy parameter decreases when oxygen is introduced in Bi2Sr2CaCu2O8+δ thick films. Further, the irreversibility line, observed by measuring electric resistance, laid on the higher magnetic field and temperature when oxygen was introduced. Therefore, the reduction of anisotropy by introducing oxygen made the electronic coupling between the CuO2 superconductor plane stronger.
