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Abstract:
We report measurements of the ab-plane resistivity (rho) and Hall
coefficient (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
other recent work on thin films, the residual resistivity of these films
(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,
continues to obey the relation, cotTHETA(H) = AT2+B. As delta increases,
the coefficient A decreases while B remains constant. Data for an
oxygen-deficient single crystal of YBa2Cu3O7-delta agree well with our
film data. Measurements of rho in the region of the superconducting
transition in fields of up to 7 T, applied parallel to the
crystallographic a, b, or c axes, are also reported. The well-known
''field-induced broadening'' of the rho(T) curves becomes larger as
delta is increased. There is evidence for a transition line in the
field-temperature plane that has the 4/3-power-law behavior associated
with critical fluctuations in the three-dimensional XY model.
