The Chemical Control of High Temperature Superconductivity

R. S. Liu ； S. F. Hu

《Chinese Journal of Physics》 34卷2S期 (1996/04) Pp. 302-309

並列摘要

In high-T, superconducting cuprates, the chemical species and composition of the hole reservoir layers are crucial to affect the hole concentration in the conducting CuO2 layers which may further result in the optimization of the superconducting transition temperature (Tc). Here, we demonstrate the effect of Tc by the variation of the chemical species in the (Pb,Cu)-0 hole reservoir layers of the Pb-based 1212-type, (Pb,Cu)Sr2(Ca,Y)Cu2O7-δ, system (Tc～45 K). The chemical substitution by (Pb,Cd)-O (Tc～70 K) or (Pb,Hg)-0 (T～90 K) or (Pb,Tl)-O(Tc～108 K) for the hole reservoir (Pb,Cu)-0 layers in the Pb-based 1212-type system can lead to the significant enhancement of Tc from 45 K to 108 K. hloreover, in each system, the amount of chemical substitution between Ca^2+ and Y^3+ is also important to control the hole concentration in the CuO2 planes and Tc. This study indicates how ”tuning” the superconductivity may be achieved by manipulating the chemical species of the hole reservoir together with the Ca/Y ratio and provides confirmation that two part nature (charge reservoir) [M2Cun+i(Ca,Y)nO2n+2] (M = Ba or Sr) of the high-T, cuprates.