Effect of high pressure on temperature dependences of the resistivity in the ab-plane of Y0.77Pr0.23Ba2Cu3O7-δ single crystals

Abstract

In the present work, we investigated the influence of high hydrostatic pressure up to 11 kbar on the conductivity in the basal ab-plane of medium-doped with praseodymium (x≈0.23) single-crystal Y1-xPrxBa2Cu3O7-δ samples. It was determined that, in contrast to the pure YBa2Cu3O7-δsamples with the optimal oxygen content, the application of high pressure leads to the formation of phase separation in the basal plane of Y0.77Pr0.23Ba2Cu3O7-δ single crystals. Possible mechanisms of the effect of Pr doping and high pressure on the two-step resistive transition to the superconducting state are discussed. It was determined that in the normal state, the conductivity is metallic and is limited by phonons scattering (Bloch-Grüneisen regime) and defects. The fluctuation conductivity is considered within the Lorentz-Doniach model. Hydrostatic pressure, accompanied by a decrease in anisotropy, leads to a decrease in the residual and phonon resistances. Debye temperature and coherence length are independent of pressure. The applicability of the McMillan formula in the presence of significant anisotropy is discussed.

Thermodynamics of Point Defects in Solids and Relation with the Bulk Properties: Recent Results

“…This model, however, does not seem to describe the case when replacing Y in the doping of YBa 2 Cu 3 O 7−δ by rare earth elements (which is strikingly reminiscent, of an earlier finding [43] that in alkali halides doped with alkaline earth divalent cations, the h m value for the reorientation process of the electric dipoles formed by a divalent cation vacancy increases upon increasing the ionic radius of the dopants but not for rare earth divalent dopant). In a work which just appeared [44], the influence of high hydrostatic pressure up to 11 kbar on the conductivity in the basal ab-plane of medium-doped with praseodymium (x ≈ 0.23) single-crystal Y 1−x Pr x Ba 2 Cu 3 O 7−δ samples was investigated and the following interesting fact emerged: in contrast to the pure YBa 2 Cu 3 O 7−δ samples with the optimal oxygen content, the application of high pressure leads to the formation of phase separation in the basal plane of Y 0.77 Pr 0.23 Ba 2 Cu 3 O 7−δ single crystals. Possible mechanisms of the effect of Pr doping and high pressure on the two-step resistive transition to the superconducting state were discussed, and it was determined that, in the normal state, the conductivity is metallic limited by phonon scattering (Bloch-Grüneisen regime) and defects.…”