Temperature dependence of positron lifetime in the two-mixed-phase Bi-Sr-Ca-Cu-O superconductor.

Abstract

We have measured the positron-lifetime spectra at different temperatures between 80 and 300 K in the two-mixed-phase Bi-Sr-Ca-Cu-O (2:2:1:2+2:2:2:3) superconductor. Above 120 K the lifetime parameters τ 1 , τ 2 , and τ are found to be independent of temperature, and below 120 K the various lifetime parameters show a significant temperature dependence: These parameters show strong irregular oscillations (discontinuous change) near 110K; near 105 K they decrease rapidly by about 10% relative to those above 120 K, and near 83 K these parameters increase again