Screening effect of interlayer coupling on electronic transport properties of layered high-$T_c$ oxides

We have investigated the effect of thermal fluctuation on the interlayer coupling of three-dimensional Josephson-junction arrays with anisotropic interactions as a model of layered high-$T_c$ oxides, focusing on non-Ohmic current-voltage characteristics. Langevin dynamic simulations were performed for various Josephson-coupling anisotropies and for various temperatures in both zero and finite magnetic fields. We find that, in the highly anisotropic region, the interlayer coupling, which causes the non-vanishing critical current ($I_{c}$), is suppressed by thermal fluctuations, and tends to push up the Kosterlitz-Thouless transition temperature ($T_{KT}$) of the two-dimensional (2D) regime. In this highly anisotropic region, $I_c$ begins to decrease drastically near $T_{KT}$. This suggests that interlayer coupling is screened by thermally excited 2D small vortex-antivortex pairs as well as the intralayer logarithmic part of vortex-antivortex interactions. Moreover, weak magnetic fields parallel to the $c$-axis affect only the logarithmic-interaction part between the 2D pancake vortices.

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