Excess Conductivity Analysis and Magneto-resistance Measurements of Cu0.5Tl0.5Ba2(Ca2-yMgy)(Cu2.5Cd0.5)O10-δ (y=0, 0.25, 0.5) Samples.

Abstract

We have studied the excess conductivity analysis and magneto-resistance of Cu0.5Tl0.5Ba2(Ca2 yMgy)(Cu2.5Cd0.5)O10-𝛿 (y=0, 0.25, 0.5) samples. Main objective of such studies is the role of decreased inter-CuO2 /CdO2-plane distance in developing the phase coherence of carriers in various superconducting planes in such superconductors. Volume of the unit cell increases and their c-axes lengths suppress in such superconductors with increased Mg doping showing enhancement of inter-plane couplings. Since such superconducting planes have Cd atoms that is heavier than Cu atoms and therefore produce an-harmonic oscillations that induces the pair breaking effects in the final compound. Room temperature resistivity of doped samples increases whereas their Tc(R=0) suppresses in doped samples. The zero resistivity critical temperature is shifts towards lower temperatures with increased strength of applied magnetic fields showing thermally activated flux flow across the pinning centers. The energy of activation such thermally activated flow suppresses with increased Mg-doping and enhance strength of applied field. Excess conductivity analyses of resistivity data of Mg-doped samples have shown increase in the coherence length along the c-axis, Fermi-velocity of carriers and critical current density. Thermodynamic critical field Bc, lower critical field Bc1 increases whereas the London penetration depth suppresses in Mg-doped samples showing increased population of the pinning centers.