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

TL;DR

This study uses simulations to explore how thermal fluctuations influence interlayer coupling and vortex behavior in layered high-$T_c$ oxides, revealing suppression of coupling and shifts in transition temperatures.

Contribution

It demonstrates the impact of thermal fluctuations on interlayer coupling and vortex interactions in anisotropic Josephson-junction arrays modeling high-$T_c$ oxides, highlighting the screening effect.

Findings

Interlayer coupling is suppressed by thermal fluctuations in highly anisotropic regions.

The critical current $I_c$ decreases sharply near the Kosterlitz-Thouless transition temperature.

Weak magnetic fields mainly affect the logarithmic vortex interactions within layers.

Abstract

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.