EFFECT OF THE IRRADIATION OF AU IONS ON THE NEGATIVE HALL RESISTIVITYFOR YBCO FILMS

The temperature dependence of longitudinal and transversal resistiviti es (rho(xx)(T) and rho(xy)(T), respectively) near the transition regio n for YBCO films have been measured before and after the irradiation o f Au ions. Our results show that the peak value of the negative rho(xy ) increases significantly at 0.5 T but remains nearly the same at 4 T after the irradiation. The power law of [rho(xy)=rho(xx)(alpha)] has b een extracted for our films, with alpha ranging from 0.9 to 1.6. There is no correlation found between the magnitude of negative rho(xy) and the alpha values. The field dependence of the irradiation effect on r ho(xy)(T) suggests a complicated interplay between the magnetic field and the defects on the mechanism of the anomalous Hall effect.