Anisotropy of the superconducting fluctuations in multiband superconductors: the case of LiFeAs

TL;DR

This paper investigates the anisotropic nature of superconducting fluctuations in LiFeAs, a layered multiband superconductor, revealing significant modulation of pairing interactions along the z direction and differences from single-band systems.

Contribution

It provides a detailed analysis of superconducting fluctuations in LiFeAs, highlighting the strong two-dimensional character and anisotropy effects in multiband superconductors.

Findings

Superconducting fluctuations exhibit strong two-dimensional behavior.

Modulation of pairing interactions occurs along the z direction.

Differences between single-band and multiband superconductors are discussed.

Abstract

Between the different families of pnictide multiband superconductors, LiFeAs is probably one of the less understood. Indeed, despite the large amount of experiments performed in the last few years on this material, no consensus has been reached yet on the possible pairing mechanism at play in this system. Here we focus on the precursor effects of superconductivity visible in the transport experiments performed above Tc. By analyzing the superconducting fluctuations in a layered multiband model appropriate for this material, we argue that the strong two-dimensional character of the paraconductivity above Tc points towards a significant modulation of the pairing interactions along the z direction. We also discuss the peculiar differences between single-band and multi-band superconductors for what concerns the anisotropy of the superconducting-fluctuations effects above and below Tc.