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

Анотація

The influence of hydrostatic pressure (HP) up to ∼1.0 GPa on resistivity, ρ(T), fluctuation conductivity (FLC), σʹ (T), and pseudogap (PG), Δ^*(T), of the Y_1−xPr_xBa₂Cu₃O_7−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 T_c at a rate dT_c/dP = +2.88 K·GPa⁻¹. From the FLC measurements, the values of the coherence length along the c-axis, ξ_c(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 T_max ~ 230 K. HP significantly increases Δ^*(T_max) as well as the slope of the descending linear section of Δ*(T) below T_max. 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 = (T_G − T_c^mf) / T_c^mf revealed completely opposite dependences of the longitudinal coherence length ξ_ab(0) on pressure for x = 0.05 and 0.34.