Strong carrier-scattering in iron-pnictide superconductors with highest Tc obtained from charge transport experiments

TL;DR

This study reveals that strong carrier scattering in oxygen-deficient iron-arsenides correlates with high superconducting transition temperatures, highlighting a distinct doping effect compared to cuprates.

Contribution

It demonstrates that carrier scattering, rather than carrier concentration, plays a key role in achieving high Tc in iron-pnictide superconductors, a novel insight.

Findings

La system with Tc=28K shows T^2 resistivity at low temperatures.

Nd system with Tc>40K exhibits T-linear resistivity and small magnetoresistance.

Strong scattering is crucial for high-Tc superconductivity in these materials.

Abstract

Characteristic normal-state charge transport is found in the oxygen-deficient iron-arsenides LnFeAsO1-y (Ln: La and Nd) with the highest Tc's among known Fe-based superconductors. The effect of "doping" in this system is mainly on the carrier scattering, quite distinct from that in high-Tc cuprates. In the superconducting regime of the La system with maximum Tc = 28 K, the low-temperature resistivity is dominated by a T^2 term. On the other hand, in the Nd system with Tc higher than 40 K, the carriers are subject to stronger scattering showing T-linear resistivity and small magnetoresistance. Such strong scattering appears crucial for high-Tc superconductivity in the iron-based system.