Longitudinal and Hall resistivity measurements were performed on an unidire
ctionally twinned YBa2Cu3O7-delta film, with current parallel and perpendic
ular to the twin boundaries, in fields up to 16 T. In the normal state, the
ratio between the longitudinal resistivity measured across and along the t
win boundaries is rho(perpendicular to)/rho(parallel to)approximate to 1.6,
while the ratio for the Hall resistivity is rho(H)(perpendicular to)/rho(H
)(parallel to)approximate to 1. These results are discussed in the framewor
k of existing theories for normal-state transport in the cuprates. In the m
ixed state, for high magnetic fields, the ratios between the longitudinal a
nd Hall resistivities diverge from the normal-state values for temperatures
below the characteristic temperature of twin boundary pinning: the ratio r
ho(perpendicular to)/rho(parallel to) increases with decreasing temperature
, whereas the ratio rho(H)(perpendicular to)/rho(H)(parallel to) decreases
with decreasing temperature; as a result, it is shown that the Hall conduct
ivity is influenced by twin boundary pinning. These high-field results are
in qualitative agreement with an extended version of the Wang, Dong, and Ti
ng model, which takes into account the anisotropy introduced by the twin bo
undaries. [S0163-1829(99)14201-2].