The Correlation between the Energy Gap and the Pseudogap Temperature in Cuprates: The YCBCZO and LSHCO Case

摘要

The paper analyzes the influence of the hole density, the out-of-plane or in-plane disorder, and the isotopic oxygen mass on the zero temperature energy gap (2 Delta(0)) Y1-xCaxBa2 (Cu1-yZny)(3)O7-delta (YCBCZO) and La1.96-xSrxHo0.04CuO4 (LSHCO) superconductors. It has been found that the energy gap is visibly correlated with the value of the pseudogap temperature (T*). On the other hand, no correlation between 2 Delta(0) and the critical temperature (T*) has been found. The above results mean that the value of the dimensionless ratio 2 Delta(0)/k(B)T(C) can vary very strongly together with the chemical composition, while the parameter 2 Delta(0)/k(B)T* does not change significantly. In the paper, the analytical formula which binds the zero temperature energy gap and the pseudogap temperature has been also presented.