Magnetoresistance studies of Tl-1212 phase substituted by scandium

Abstract

Superconducting samples of TlBa 2 CaCu 2−x Sc x O 7−δ with x = 0.0, 0.025, 0.05, 0.1, 0.15 and 0.2 have been prepared via the solid-state reaction technique. The effect of weak magnetic fields up to 4.4 kG on the electrical resistivity of the prepared samples has been studied to investigate the flux motion for this phase. The results reveal a slight shift in the superconducting transition temperature T c and an increase in the superconducting transition width T with increasing magnetic field. The magnetic field has a small effect on the electrical resistivity in the normal state and in the first stage of transition, whereas the change in the second stage of superconducting transition is very large. The experimental data, in the second stage of superconducting transition, fit well with the thermally activated flux creep model and the activation energy U (B) shows a power law dependence on magnetic field as B −β . Also, the transition width is related to the magnetic field according to the relation T α B n . The values of β and n are strongly dependent on the scandium content. The magnetic field and temperature dependence of the activation energy U (B, T ) is found to be U (B, T ) ∼ T B −η , where η = β + n. The critical current density J c (0) and the upper critical field B c2 (0) are calculated, from the above measurements, as a function of scandium content. Finally, the electronic thermal conductivity κ e , estimated from the Wiedermann-Franz law, is reported at different applied magnetic fields for the prepared samples.

Magnetoresistivity studies for BiPb-2223 phase added by BaSnO3 nanoparticles

“…12 by further increase in T. However, the suppression in the electronic thermal conductivity by increasing B below the superconducting transition temperature is probably due to the additional scattering centers of vortices [48]. Above the superconducting transition temperature, e  is magnetic field independent [33].…”

“…In AH theory, the physical picture of the normalized barrier height makes the separation of magnetic field effect and thermal effect in the normalized barrier height achieved as ( , ) ( )(1 ) [32,33], and ( ) C B is a magnetic field dependent parameter from which the critical current density at 0 K can be calculated using the following relation [30]: …”

Magnetoresistance studies of Tl-1223 phase substituted by scandium

“…. Using the above equations and many mathematical treatments, discussed by Mohammed et al [15], we can find the dependence of U on both T and B:…”

Synthesis, Characterization and Magnetoresistance Studies of Tl0.5Pb0.5Sr1.6Ba0.4CaCu2−x Ru x O7−δ Superconductor

“…In addition, similar upturn in the electrical resistivity behavior was observed with x = 0. 15 [16] phases, respectively. For x = 0.525, a semiconductor-like behavior, in the whole temperature range, is observed.…”

“…The highest T c was found with x = 0.2, while the highest transport critical currents as well as the irreversibility fields was found with x = 0.1. The magnetoresistance studies of TlBa 2 CaCu 2−x Sc x O 7−δ phase were analyzed according to TAFC model and AH theory [15]. The enhancement of both the flux pinning energy and the critical current density was recorded up to x = 0.05.…”