Doping Dependence of Hall Coefficient and Evolution of Coherent Electronic State in the Normal State of Fe-based Superconductor Ba$_{1-x}$K$_{x}$Fe$_{2}$As$_{2}$

TL;DR

This study explores how doping affects the Hall coefficient and electronic coherence in Ba$_{1-x}$K$_{x}$Fe$_{2}$As$_{2}$, revealing a transition to a coherent state with heavy quasiparticles below 100 K.

Contribution

It provides a detailed analysis of the doping dependence of transport properties and identifies the emergence of a coherent electronic state in Fe-based superconductors.

Findings

Hall coefficient follows a two-band Boltzmann model with a rigid band approximation.

Heavy hole carriers conduct more smoothly than electrons.

Anomalous coherent state with heavy quasiparticles develops below 100 K in certain doping regions.

Abstract

We investigated the in-plane transport properties of the Fe-based superconductor Ba$_{1-x}$K$_{x}$Fe$_{2}$As$_{2}$ with a wide composition range $0 \leq x \leq 0.55$. We show that the doping dependence of the Hall coefficient is well-described by the Boltzmann equation for a two-band system with a rigid-band approximation. We successfully deduced transport parameters, which suggested that holes with heavier mass conduct more smoothly than electrons. Moreover, the temperature variation of the Hall coefficient indicated that an anomalous coherent state characterized by heavy quasiparticles in hole bands evolved below $\sim100$ K, predominantly in the optimal and overdoped regions. We argue that this phenomenon can be understood in relation to the pseudopeak structure observed in angle-resolved photoemission spectroscopy.