BROADENING OF RESISTIVE TRANSITION AND IRREVERSIBILITY LINE FOR EPITAXIAL YBA2CU3O7-DELTA THIN-FILM

The broadening of resistive transition of c axis oriented epitaxial YB CO thin film has been measured for three configurations: (1) H paralle l to c and H perpendicular to I; (2) H parallel to ab plane and H perp endicular to I; (3) H parallel to ab plane and H parallel to I in magn etic field up to 8 Tesla(T), and for different angle theta of magnetic held relative to the ab plane with H = 4T. The results obtained indic ate that the broadening of resistive transition is mainly determined b y the angle theta, but is hardly related to the angle a made between m agnetic held and transport current in ab plane. This means that the br oadening of resistive transition is not determined by flux motion driv ed by apparent Lorentz force. An expression of angular dependence of i rreversibility line has been given.