OBSERVATION OF VISCOUS FLUX-FLOW IN YBA2CU3O7-DELTA LOW-ANGLE GRAIN-BOUNDARIES

The dynamics of vortices within an YBa2Cu3O7-delta low-angle grain bou ndary have been investigated by means of current-voltage measurements with a magnetic field applied in the plane of the boundary. The high e lectric field regime can be explored without significant heating of th e sample because the gauge length for the flux flow is of order the in tervortex spacing, enabling the accurate determination of the flux flo w resistivity rho(f). It is observed that the well-known phenomenologi cal expression rho(f)/rho(n)approximate to B/B-c2 remains valid. The e ffect of the anisotropy of the superconductor on flux Row is also expe rimentally investigated.