Abstract
Our recent measurements of positron lifetime (related to electron density at the annihilating sites) components or τ i and Doppler broadening of positron annihilation radiation lineshape or S-parameter (denoting the fraction of low-momentum electrons among the annihilating electrons) on Bi-2212 and (Bi,Pb)-2223 pellets and Y-123 single crystals firstly confirm step-like changes across T c. Our second and new observation is that S versus T graph in the superconducting transition region shows a double minimum for 2223 and 123 and a single minimum for 2212. These steps and minima, not seen for superconductors like Nb 3Sn, are linked to such features of HTSC electronic structure as are not found in conventional superconductors.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
