Thermoelectric studies of KxFe2-ySe2: weakly correlated superconductor

TL;DR

This study investigates the thermal transport properties of KxFe2-ySe2, revealing it as a weakly or intermediately correlated superconductor with unique phonon and thermoelectric characteristics.

Contribution

The paper provides new thermal transport measurements of KxFe2-ySe2, highlighting its weak correlation and distinct thermoelectric behavior compared to other iron-based superconductors.

Findings

Peak anomaly in thermal conductivity at ~TC/2

Small thermoelectric power indicating large Fermi temperature

Lack of significant thermoelectric anomalies unlike other iron superconductors

Abstract

We report thermal transport measurement of KxFe2-ySe2 superconducting single crystal. Significant peak anomaly in thermal conductivity is observed at nearly TC/2 indicating a large phonon mean-free-path in the superconducting state. The zero-temperature extrapolated thermoelectric power is smaller than the value in typical strongly correlated superconductors, implying large normalized Fermi temperature. In contrast to other iron superconductors, thermoelectric power in our sample does not exhibit significant anomalies. These findings indicate that KxFe2-ySe2 is a weakly or intermediately correlated superconductor without significant Fermi surface nesting.