Vortex phase diagram and transition in (Bi1.6Pb0.4Sr2Ca2Cu3O10-δ)1-x(SnO2)x superconductors

Abstract

The superconducting vortex phase diagram of (Bi1.6Pb0.4Sr2Ca2Cu3O10-δ)1-x(SnO2)x ceramics, where x = 0, 0.002, 0.004, 0.006, 0.008, and 0.010, was investigated using resistivity measurement under magnetic fields. If the value of the offset critical temperature (Tc,offset) monotonously decreased on the SnO2-added samples, then the mean-field critical temperature (Tmf) would slightly improve on the x = 0.002 sample. The excess conductivity of all samples was analyzed based on the Aslamazov–Larkin and Lawrence–Doniach models. The c-axis coherence length at 0 K (ξc(0)) and the interlayer coupling strength were optimized on the x = 0.002 sample. The activation energy (U0) calculated using the Arrhenius model was also increased, and the maximum for the x = 0.002 sample was reached. The upper critical field (Bc2) deduced using the Werthamer–Helfand–Hohenberg model was also enhanced for the x = 0.002 sample. The small bundle field (Bsb), large bundle field (Blb), irreversibility field (Birr), and Bc2 were combined for the vortex phase (B-T) diagram of the x = 0.000 and x = 0.002 samples. All pinning regimes of the x = 0.002 sample were extended, clearly revealing the improvements in the flux pinning properties in that sample.

Keywords

• BSCCO
• SnO2 nanoparticle
• Excess conductivity
• Upper critical field
• Pinning potential