Effect of hydrostatic pressure on the conductivity of YBa2Cu3O7-δsingle crystals in a broad range of temperature and oxygen content

The effect of external hydrostatic pressure on the electrical resistance of optimally doped and underdoped YBa2Cu3O7-δ single crystals is investigated in a broad temperature range, which includes the normal state and the region of superconducting fluctuations. The temperature dependences of the resistivity in the normal state are determined by scattering of charge carriers by phonons and defects. The application of pressure leads to significant changes in the electronic structure of the sample and reduces the degree of their defectiveness. This is accompanied by changeû in the lattice characteristics as the sample volume decreases. The fluctuation conductivity only exists within the range of ∼0.1Tc. With increasing δ the superconducting characteristics are close to the values typical for conventional low-temperature superconductors.