Distinct transport behaviors of LaFe1-yCoyAsO1-xFx (x=0.11) between the superconducting and nonsuperconducting metallic y regions divided by y ~ 0.05

TL;DR

This study investigates the transport properties of LaFe1-yCoyAsO1-xFx across different doping levels, revealing a clear boundary at y~0.05 that separates superconducting and nonsuperconducting metallic behaviors, similar to high-Tc cuprates.

Contribution

It identifies a distinct boundary in doping levels that separates different transport behaviors and compares these behaviors to high-Tc cuprates, providing insights into magnetic fluctuations and electronic nature.

Findings

Transport behaviors differ sharply at y~0.05 boundary.

Both regions show similarities to high-Tc cuprates.

Small Tc suppression rate suggests specific electronic and pairing characteristics.

Abstract

Electrical resistivities, Hall coefficients and thermoelectric powers have been measured for polycrystalline samples of LaFe1-yCoyAsO1-xFx (x=0.11) with various values of y. The results show that there exists clear distinction of these transport behaviors between the superconducting and nonsuperconducting metallic regions of y divided by the boundary value yc~0.05. We have found that the behaviors in both regions are very similar to those of high-Tc Cu oxides in the corresponding phases. If they reflect, as in the case of Cu oxides, effects of strong magnetic fluctuations, the energy scale of the fluctuations is considered to be smaller than that of the high Cu oxides by a factor of ~1/2. Arguments on the electronic nature and superconducting symmetry are presented on the basis of the observed small rate of the Tc suppression rate by the Co doping.