Vortex-unbinding and finite-size effects in Tl2Ba2CaCu2O8 thin films

Abstract

Current-voltage ($I$-$V$) characteristics of Tl${}_2$Ba${}_2$CaCu${}_2$O${}_8$ thin films in zero magnetic field are measured and analyzed with the conventional Kosterlitz-Thouless-Berezinskii (KTB) approach, dynamic scaling approach and finite-size scaling approach, respectively. It is found from these results that the $I$-$V$ relation is determined by the vortex-unbinding mechanism with the KTB dynamic critical exponent $z=2$. On the other hand, the evidence of finite-size effect is also found, which blurs the feature of a phase transition.

Typo corrected & reference added