The correlation between the energy gap and the pseudogap temperature in cuprates: the YCBCZO and LSHCO case

TL;DR

This study investigates the relationship between the energy gap and pseudogap temperature in specific cuprate superconductors, revealing a strong correlation with pseudogap temperature but not with critical temperature, and provides an analytical formula linking these parameters.

Contribution

The paper introduces an analytical formula connecting the zero temperature energy gap with the pseudogap temperature in cuprate superconductors, highlighting the distinct correlations with different temperature scales.

Findings

Energy gap correlates with pseudogap temperature ($T^{igstar}$).

No correlation found between energy gap and critical temperature ($T_C$).

The ratio $2igtriangleup(0)/k_B T^{igstar}$ remains relatively constant.

Abstract

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 ($2\Delta\left(0\right)$) for $\rm{Y}_{1-x}\rm{Ca}_{x}\rm{Ba}_2\left(\rm{Cu}_{1-y}\rm{Zn}_{y}\right)_{3}\rm{O}_{7-\delta}$ (YCBCZO) and $\rm{La}_{1.96-x}\rm{Sr}_{x}\rm{Ho}_{0.04}\rm{CuO}_{4}$ (LSHCO) superconductors. It has been found that the energy gap is visibly correlated with the value of the pseudogap temperature ($T^{\star}$). On the other hand, no correlation between $2\Delta\left(0\right)$ and the critical temperature ($T_{C}$) has been found. The above results mean that the value of the dimensionless ratio $2\Delta\left(0\right)/k_{B}T_{C}$ can vary very strongly together with the chemical composition, while the parameter $2\Delta\left(0\right)/k_{B}T^{\star}$ 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.