HALL AND THERMOELECTRIC-POWER COEFFICIENTS OF SUPERCONDUCTING ND2CUO4-XFX

Both the Hall coefficient (R(H)) and the thermoelectric-power coefficient (S) have been measured using the same polycrystalline samples of superconducting Nd2CuO4-xFx (0 less-than-or-equal-to x less-than-or-equal-to 0.3). For the samples with 0.1 less-than-or-equal-to x less-than-or-equal-to 0.3, the R(H) of every sample is found to be negative in the temperature range between 30 and 275 K. Furthermore, as x increases, the charge-carrier density (P(H)) estimated from R(H) at 100 K increases in proportion to x (p(H) = x) up to around 0.18, then much more rapidly for x greater-than-or-equal-to 0.18. On the other hand, the S of every sample is also found to be negative in the temperature range between 30 and 300 K. The absolute value of S is found to reduce with x up to around 0.18 and then level off to a constant value as x increases further to 0.3. The decrease in \S\ due to F doping is discussed using a semiconductor model. In addition, we point out a possibility that a magnon drag plays a significant role in S for samples with x < 0.18.