The influence of hydrostatic pressure up to P=1.05 GPa on resistivity R, excess conductivity σ′(T) and pseudogap Δ∗(T) is studied in slightly doped single crystals of YBa2Cu3O7-δ(Tc=49.2K,δ0.5). The critical temperature Tc is found to increase with increasing pressure at a rate dTc/dP = 5.1 K/GPa, while R(300)K decreases at a rate d(ln R)/dP = 0.19% 1/GPa. Near Tc, independently on pressure, the σ′(T) is well described by the Aslamasov-Larkin and Hikami-Larkin fluctuation theories, demonstrating a 3D-2D crossover with increase of temperature. The crossover temperature To determines the coherence length along the c-axis ξc(0)∼3.43A at P=0, which is found to decrease with increasing P. At the same time, both, Δ∗ and the BCS ratio 2Δ∗/kTc increase with increasing hydrostatic pressure at a rate d(lnΔ∗)/dP=0.361/GPa, implying an increase of the coupling strength with increasing P. At low temperatures below Tp, the shape of the Δ∗(T) curve is found to be almost independent on pressure. At high temperatures, the shape of the Δ∗(T) curve changes noticeably with increasing P, suggesting a strong influence of pressure on the lattice dynamics. This unusual behavior is observed for the first time.
@article{arxiv.1708.00340,
title = {Hydrostatic-pressure effects on the pseudogap in slightly doped YBa2Cu3O7-{\delta} single crystals},
author = {A. L. Solovjov and L. V. Omelchenko and R. V. Vovk and O. V. Dobrovolskiy and D. M. Sergeyev},
journal= {arXiv preprint arXiv:1708.00340},
year = {2017}
}