Determination of the gap in Bi-Sr-Ca-Cu-O (2:2:1:2-phase) superconducting whiskers by tunneling spectroscopy
Borisova I. A., Ponomarev Ya. G., Rakhimov Kh. T., Sudakova M. V., Tsokur E. B., Shcherbakov N. A., Yarygin A. V., Kraak W., Krapf A., Os'kina T. E., Tret'yakov Yu. D.
The current-voltage characteristics of break junctions in Bi-Sr-Ca-Cu-O whiskers (the 2:2:1:2 phase), with a transition temperature 60 <ГС<81 К, have been studied experimentally. These /^characteristics have a gap structure which is easily reproducible. From it one can determine the gap parameter Δ fairly accurately. In the interval of transition temperatures Tc studied, the ratio 2A(0)/kTc for the Bi-Sr-Ca-Cu-O (2:2:1:2) whiskers is 7.1 ±0.2. The temperature dependence of the gap, Δ(Γ), agrees satisfactorily with the formal BCS theory.