Angular dependence of critical currents in Bi2Sr2CaCu2O8 thin films predominant role of the transverse magnetic field component

We have studied the critical current of c-axis oriented Bi2Sr2CaCu208 thin films measured at various temperatures as a functionof magnitude (H_< 20 T) and orientation 0 (with respect to the c-axis) of the applied magnetic field. The curves J¢ (0) at a givenfield H show a strong maximum when H is parallel to the CuO2 planes (0=90 ° ). For 0¢90 °, we show that J¢ depends only onthe component of the magnetic field along the c direction in the whole temperature range. In particular, at 4.2 K, J~(H, O) behavesas [Hcos 01 -'~ with 0.44-< a < 0.5. These results agree with the recent scaling theory proposed by Blaner et aL describing thebehaviour of anisotropic superconductors for an arbitrary angle between the magnetic field and the anisotropic crystallographicaxis.