Effect of Li-deficiency impurities on the electron-overdoped LiFeAs superconductor

TL;DR

This study reveals that LiFeAs is intrinsically electron-overdoped and that Li deficiencies suppress superconductivity mainly through impurity scattering, despite similar electronic and magnetic properties.

Contribution

It demonstrates that Li-deficiency impurities in LiFeAs suppress superconductivity by impurity scattering, even though the electronic and magnetic properties remain similar to the stoichiometric compound.

Findings

LiFeAs is an intrinsically electron-overdoped superconductor.

Li deficiencies suppress superconductivity via impurity scattering.

Electronic and magnetic properties are similar in both stoichiometric and Li-deficient samples.

Abstract

We use transport, inelastic neutron scattering, and angle resolved photoemission experiments to demonstrate that the stoichiometric LiFeAs is an intrinsically electron-overdoped superconductor similar to those of the electron-overdoped NaFe1-xTxAs and BaFe2-xTxAs2 (T = Co,Ni). Furthermore, we show that although transport properties of the stoichiometric superconducting LiFeAs and Li-deficient nonsuperconducting Li1-xFeAs are different, their electronic and magnetic properties are rather similar. Therefore, the nonsuperconducting Li1-xFeAs is also in the electron overdoped regime, where small Li deficiencies near the FeAs octahedra can dramatically suppress superconductivity through the impurity scattering effect.