Weak link behavior of Be doped (Cu0.5K0.25Tl0.25)Ba2(Ca3−xBex)Cu4O12−δ superconductors

A systematic study of the weak link behavior for Be doped (Cu0.5K0.25Tl0.25)Ba2(Ca3−xBex)Cu4O12−δ (x=0,0.5,0.75,1.0,1.25,1.5) superconductors is carried out. Calcium atom in the unit cell of aforementioned compound separates the conducting CuO2 planes and the doping of smaller sized beryllium at those sites would enhance the interplane coupling. The critical temperature and magnitude of diamagnetism have been found to increase with increased Be doping concentrations up to x=1.25. For Be doped samples, the Tc(R=0) and magnitude of diamagnetism is enhanced further with the postannealing in oxygen atmosphere. The increased magnitude of diamagnetism after postannealing in oxygen atmosphere is most likely accomplished by the optimization of carriers in the conducting CuO2 planes. It is observed in the infield magnetic measurements that peak temperature (Tp) in the Be doped samples postannealed in oxygen atmosphere survives to much higher external magnetic fields as compared to Be free samples. These observatio...