Comment on "Multiorbital Effects on the Transport and the Superconducting Fluctuations in LiFeAs"

TL;DR

This paper critically examines a previous claim that LiFeAs exhibits two-dimensional fluctuation conductivity near Tc, suggesting that the original conclusion may result from improper data analysis rather than actual physical behavior.

Contribution

The authors demonstrate that the previously reported 2D fluctuation behavior in LiFeAs is likely an artifact caused by inadequate subtraction of the normal-state contribution.

Findings

The 2D behavior is not supported after proper data analysis.

LiFeAs exhibits three-dimensional fluctuation behavior near Tc.

The original claim may be due to data analysis artifacts.

Abstract

In the commented work (PRL 109, 187005 (2012)), Rullier-Albenque et al. present measurements of transverse magnetoresistivity above the transition temperature Tc in clean LiFeAs. By analyzing their data, these authors conclude that the conductivity induced by fluctuations follows a two-dimensional (2D) behavior even close to Tc, in spite that for LiFeAs the transverse coherence length ($\xi_c$(0)=1.6 nm) is larger than the Fe-layers spacing (s=0.636 nm), which would rather suggest a three-dimensional (3D) behavior. This striking proposal would have deep implications in the theoretical understanding of the multiband structure of iron pnictides, but it also contrasts with the 3D behavior observed near Tc in the same compound and in other iron pnictides with even smaller $\xi_c$(0)/s ratios. Here we show that the proposal of Rullier et al. could be just an artifact associated to an inadequate subtraction of the normal-state contribution.