FIELD-INDUCED CROSSOVER OF CRITICALITIES OF VORTEX DYNAMICS IN TL2BA2CACU2O8 THIN-FILMS

By analyzing I-V characteristics (E-B curves), which were experimental ly determined on Tl2Ba2CaCu2O8 thin films in magnetic fields B-e varyi ng from 0 T to 5 T, we find that the transition of the linear resistiv ity rho(lin) = [E/j](j-->0) signaling superconductivity exhibits diffe rent criticalities for different magnetic fields. Starting with a Bere zinskii-Kosterlitz-Thouless transition at T-BKT = 103.7 It for B-e = 0 T, one induces a crossover to a quasi-2D or 3D vortex-glass transitio n at a finite T-g for magnetic fields below a few kOe, and finally a ' 'true'' 2D vortex-glass with T-g = 0 K for higher fields. We argue tha t this field-induced crossover of criticalities is a general feature o f all strongly anisotropic high-T-c superconductors.