Hydrostatic pressure effect on the pseudogap in Y0.66Pr0.34Ba2Cu3O7–δ single crystals

The influence of hydrostatic pressure (HP) up to ∼1.0 GPa on resistivity, ρ(T), fluctuation conductivity (FLC), σ′(T), and pseudogap (PG), Δ*(T), of the Y1−xPrxBa2Cu3O7−δ (x = 0.34) single crystal was studied in detail. Defects created by magnetic inclusions of PrBCO were shown to play a significant role in the behavior of the sample. As expected, pressure decreased ρ(T) at a rate dln ρ/dP = ̶ (16.5 ± 0.2) % GPa–1 at T = 100 K and increased Tc at a rate dTc/dP = + 2.88 K⋅GPa−1. From the FLC measurements, the values of the coherence length along the c-axis, ξc(0), were obtained, which decrease slightly under pressure. The PG analysis revealed a rather specific shape of Δ*(T) with a pronounced magnetic maximum at Tmax ∼ 230 K. HP significantly increases Δ*(Tmax) as well as the slope of the descending linear section of Δ*(T) below Tmax. As a result, the shape of Δ*(T) becomes almost the same as in FeAs-based magnetic superconductors. A comparative analysis of the influence of pressure on the shape of Δ*(T) was conducted for different Pr content in the sample. Measurements of the Ginzburg number Gi=(TG−Tcmf)/Tcmf revealed completely opposite dependences of the longitudinal coherence length ξab(0) on pressure for x = 0.05 and 0.34.