Magnetoresistance and Hall effect in unidirectionally twinned YBa2Cu3O7-delta thin films

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].