HALL-EFFECT AND RESISTIVITY OF OXYGEN-DEFICIENT YBA2CU3O7-DELTA THIN-FILMS

We report measurements of the ab-plane resistivity (rho) and Hall coef ficient (R(H)) of crystalline thin films of YBa2Cu3O7-delta (0.05 less -than-or-equal-to delta less-than-or-equal-to 0.53) from below T(c) up to 400 K. In contrast to measurements on sintered samples, and some o ther recent work on thin films, the residual resistivity of these film s (as extra-polated from high temperature) remains low for all delta. As oxygen is removed from the films, rho increases and rho(T) develops downward curvature below 300 K. The Hall angle (THETA(H)) however, co ntinues to obey the relation, cotTHETA(H) = AT2+B. As delta increases, the coefficient A decreases while B remains constant. Data for an oxy gen-deficient single crystal of YBa2Cu3O7-delta agree well with our fi lm data. Measurements of rho in the region of the superconducting tran sition in fields of up to 7 T, applied parallel to the crystallographi c a, b, or c axes, are also reported. The well-known ''field-induced b roadening'' of the rho(T) curves becomes larger as delta is increased. There is evidence for a transition line in the field-temperature plan e that has the 4/3-power-law behavior associated with critical fluctua tions in the three-dimensional XY model.