AB-PLANE ANISOTROPY OF TRANSPORT-PROPERTIES IN UNIDIRECTIONALLY TWINNED YBA2CU3O7-DELTA FILMS

A unidirectionally twinned, c oriented YBa2Cu3P7-delta film was prepar ed on a (001) NdGaO3 substrate. In the normal state between 100 and 30 0 K, the unidirectional twin plane lattice induces a strong anisotropy of rho(ab), leading to a temperature independent ratio of 6 between t he resisitivities across and along the twin boundaries. At 77 K, the s elf-field critical current parallel to twin planes is 1.2 x 10(6) A/cm (2), a value which is 25 times higher than along the perpendicular dir ection. This shows that, at this temperature, twin boundaries control the critical current values in YBCO films by either channeling or pinn ing effects.