Peculiarities of pseudogap in Y0.95Pr0.05Ba2Cu3O7−δ single crystals under pressure up to 1.7 GPa

Abstract

The effect of hydrostatic pressure up to P = 1.7 GPa on the fluctuation conductivity σ′(T) and pseudogap ∆*(T) in Y_0.95Pr_0.05Ba₂Cu₃O_7−δ single crystal with critical temperature Т_с = 85.2 K (at P = 0) was investigated. The application of pressure leads to the increase in T_c with dT_c/dP = +1.82 K∙GPa⁻¹ while the resistance decreases as dlnρ(100 K)/dP = −(10.5 ± 0.2) %∙GPa⁻¹. Regardless of the pressure, in the temperature interval from T_c to T₀ (~88 K at P = 0) the behaviour of σ′(T) is well described by the Aslamazov – Larkin (AL – 3D) fluctuation theory, and above the T₀ by the Lawrence – Doniach theory (LD). The Maki-Thompson (MT – 2D) fluctuation contribution is not observed. This indicates the presence of structural defects in the sample induced by Pr. Here it is determined for the first time that when the pressure is applied to the Y_1−xPr_xBa₂Cu₃O_7−δ single crystal, the pseudogap increases as dlnΔ*/dP = 0.17 GPa^–1.