ANISOTROPIC PRESSURE-DEPENDENCE OF THE CRITICAL-TEMPERATURE OF REBA2CU3O7-DELTA

The hydrostatic pressure dependence of the superconducting critical temperature, T(c), was measured in highly crystalline oriented REBa2Cu3O7-delta (RE = Yb, Dy, Y, Gd) thin films grown on different substrates. The anisotropic strain field induced by the substrate and the different crystalline orientations of the films allows the three strain derivatives of the critical temperature to be estimated. A large anisotropy is found in the ab plane with T(c) increasing on compression parallel to the CuO chains and decreasing on compression perpendicular to them. The results on c textured films indicate a non linear relation between T(c) and the microscopic parameter which determines its pressure dependence.