Relaxation of the electric resistance of YBaCuO single crystals due to hydrostatic pressure and jumpwise temperature variation

The effect of hydrostatic pressure on pressure, temperature, and time depen dences of the conductivity in the ab-plane of YBa2Cu3O7-x single crystals w ith different oxygen concentrations (0.1 < x < 0.5) is studied. It is shown that in oxygen-deficient samples with x > 0.2, temperature and pressure va riations may induce a nonequilibrium state in which effects associated with the variation of unit cell volume and redistribution of oxygen in Cu-O pla nes must be distinguished. Characteristic conductivity relaxation times und er the effect of pressure and during annealing at room temperature are dete rmined. It is concluded that these processes have the same origin. (C) 1999 American Institute of Physics. [S1063-777X(99)00312-6].