NORMAL STATE TRANSPORT-PROPERTIES IN SUPERCONDUCTING OXIDES RBA2CU3O7-DELTA (R = Y, GD, SM, ND AND DY)

The resistivity, Hall coefficient, magnetoresistance and thermoelectric power of the sintered superconducting oxides RBa2Cu3O7-delta (R = Y, Gd, Sm, Nd and Dy) have been measured in the temperature range 80 to 300 K. It is observed that the superconducting transition temperature does not change upon replacing Y by rare earth ions. The resistivity and thermoelectric power increases with temperature increase in the normal state in all the samples. A correlation between the Hall coefficient and thermoelectric power, along with the assumption that the holes introduced in the top full band by the doping of oxygen atoms are the current carriers, reveals the effective mass of the carriers to be temperature dependent. The temperature variations of the resistivity, Hall coefficient and thermoelectric power have been explained well by the temperature-dependent effective mass of holes and hole-phonon scattering. The concentration, mobility, effective mass and Fermi energy of carriers have been calculated.