Direct observation of local K variation and its correlation to electronic inhomogeneity in (Ba1-xKx)Fe2As2 Pnictide

TL;DR

This study directly observes local potassium variation and its link to electronic inhomogeneity in (Ba1-xKx)Fe2As2, revealing dopant clustering and phase coexistence in pnictide superconductors.

Contribution

First direct atom probe tomography evidence of dopant nano-clustering in K-doped pnictides and insights into phase coexistence from first-principles calculations.

Findings

Dopant nano-clusters observed via atom probe tomography.

Evidence of phase coexistence and separation related to dopant distribution.

Static magnetism and superconductivity coexistence over various doping levels.

Abstract

Local fluctuations in the distribution of dopant atoms are a suspected cause of nanoscale electronic disorder or phase separation observed within the pnictide superconductors. Atom probe tomography results present the first direct observations of dopant nano-clustering in a K-doped 122-phase pnictides. First-principles calculations suggest the coexistence of static magnetism and superconductivity on a lattice parameter length scale over a large range of doping concentrations. Collectively, our results provide evidence for a mixed scenario of phase coexistence and phase separation originating from variation of dopant atom experiments distroibutions.