The role of twins in the change of the conductivity characteristics of HoBa₂Cu₃O_7-δ single crystal in a reversible change of hydrostatic pressure

The in-plane electrical resistivity of HoBa₂Cu₃O_7-δ single crystal (T_c = 62-66 K) in the range of T_c-300 K has been investigated under conditions, when the measuring current flows parallel to twins, or at an angle of 45 deg to them in the process of reversible changes in hydrostatic pressure. The analysis of the changes in Tc, the parameters of the Bloch-Grueneisen equation and the fluctuation conductivity parameters in the model Aslamazov.Larkin was made. The application of pressure contributes to the appearance of the second phase with a lower Tc, which is more clearly seen in the case of measuring current crossing the twinning plane. In this case, the transverse coherence length and the interval of the existence of the fluctuation conductivity are smaller than in the first configuration. The relaxation of parameters characterizing the scattering of charge carriers by phonons and defects associated with the redistribution of oxygen between the two phases.