Enhancement of superconducting fluctuation under the coexistence of a competing pseudogap state in Bi2Sr2-xRxCuOy

摘要

The onset temperature of superconducting fluctuation Tonset of Bi2Sr2-xRxCuOy(R=La and Eu) was studied by measuring the Nernst effect. We found that Tonsethas a x and R dependence that is quite different from both the pseudogaptemperature T* and the critical temperature Tc. Our results support the picturethat the incoherent superconductivity, which has been observed below Tonset, isqualitatively different from the pseudogap phenomenon that is characterized byT*. The experimentally obtained phase diagram indicates that the pseudogapstate suppresses Tc and enhances superconducting fluctuation while having onlysmall influence on Tonset.