Hydrostatic pressure effect on the pseudogap in Y0.77Pr0.23Ba2Cu3O7-δsingle crystals

We studied the changes of resistivity $\rho(T)$, superconducting transition temperature $T_c$, fluctuation conductivity $\sigma'(T)$, and pseudogap $\Delta^*(T)$ of $Y_{1-x}Pr_xBa_2Cu_3O_{7-\delta}$ (YPrBCO) ($x = 0.23$) single crystal under hydrostatic pressure (HP) up to $\sim 1.1$ GPa. Defects created by magnetic inclusions of $PrBa_2Cu_3O_{7-\delta}$ (PrBCO) were found to play a significant role in the behavior of the sample. The largest decrease in $\rho(T)$ was found depending on HP at a rate of $d\ln\rho(100~K)/dP = -(29 \pm 0.2) \% \cdot GPa^{-1}$. This indicates that the mechanisms of the influence of HP on the $\rho(T)$ and $T_c$ of YPrBCO and $YBa_2Cu_3O_{7-\delta}$ single crystals are different. From the analysis of the pseudogap, it was revealed that the mechanism of the interaction of charge carriers with magnetic PrBCO impurities changes three times with increasing HP. Relatively low HP, up to $\sim 0.5$ GPa, promotes the formation of defects caused by PrBCO magnetic inclusions. Starting from 0.6 GPa, the HP neutralizes the influence of magnetic impurities, and the magnetic maximum on $\Delta^*(T)$ disappears. Above $\sim 1.0$ GPa, HP aligns the magnetic moments of PrBCO, and the magnetic maximum reappears on $\Delta^*(T)$, more pronounced than at $P = 0$.