POSITIVE HALL-COEFFICIENT OBSERVED IN SINGLE-CRYSTAL ND2-XCEXCUO4-DELTA AT LOW-TEMPERATURES

The Hall coefficient R(H) has been measured in superconducting single crystals of Nd(2-x)Ce(x)CuO4-delta(x approximately 0.15). Although R(H) is sample dependent in sign above approximately 100 K, it increases steeply to positive values in all crystals studied below approximately 80 K. R(H) remains T (temperature) dependent at 2 K, in contrast to the resistivity rho-a which saturates to a constant below 30 K. Using a two-band model, we account for the observed profiles of R(H) vs T and rho-a vs T. The analysis reveals that the scattering processes for the electronlike and holelike bands have vastly different temperature scales. The hole-scattering rate remains T dependent to 2 K. The question whether the hole or the electron quasiparticles are responsible for the superconductivity in Nd(2-x)Ce(x)CuO4-delta is discussed.