Abstract
A pseudo dc flux transformer configuration shows that the flux flow in La
2−xSr
xCuO
4 (x=0.075) and YBa
2Cu
3O
7 single crystals is due to the movement of 3-D vortices across the sample. We show that the loss of c-axis long range vortex correlation is achieved either by thermal fluctuations or by an inhomogeneus Lorentz force acting on the vortices.