Anisotropic zero-resistance onset in organic superconductors

TL;DR

This paper explains the anisotropic zero-resistance onset in organic superconductors by modeling isolated superconducting islands within the material, considering sample shape and size, and offers a method to estimate their volume and size.

Contribution

It introduces a model that accounts for sample shape and size to explain anisotropic superconducting onset and estimates the properties of superconducting islands in inhomogeneous materials.

Findings

Anisotropic resistance drop explained by nascent SC islands.

Finite size and shape of samples are crucial for SC onset.

Method to estimate volume and size of SC islands.

Abstract

We study the coexistence of superconductivity (SC) and density-wave state and reconcile various puzzling experimental data in organic superconductors (TMTSF)$_{2}$PF$_{6}$ and (TMTSF)$_{2}$ClO$_{4}$. The anisotropic resistance drop above $T_c$ is qualitatively described by nascent isolated SC islands within a bulk analytical model. However, the observed anisotropic SC onset is explained only when the finite size and flat needle shape of samples is considered. Our results pave a way to estimate the volume fraction and the typical size of SC islands in far from the sample surface, and apply to many inhomogeneous superconductors, including high-$T_c$ cuprate or Fe-based ones.