HALL-EFFECT OF VORTICES PARALLEL TO CUO2 LAYERS AND THE ORIGIN OF THE NEGATIVE HALL ANOMALY IN YBA2CU3O7-DELTA

The Hall resistivity of vortices that lie parallel to the CuO2 layers in YBa2Cu3O7-delta is shown to be negative, in contrast with the Hall effect observed with field perpendicular to the layers (H parallel-to c). The Magnus force component along the current is opposite in sign for vortices that lie parallel and perpendicular to the layers. In an oblique field, the opposing forces strongly influence vortex motion. This finding provides new insight into the negative Hall anomaly (observed with H parallel-to c). We show that the anomaly arises from the negative sign of the interlayer segments produced by strong fluctuations about the direction of H.