The anomaly Cu doping effects on LiFeAs superconductors

TL;DR

This study investigates how copper doping affects the superconducting properties of LiFeAs, revealing minimal doping effects on Fermi surfaces compared to cobalt or nickel, and highlighting differences in lattice parameter changes.

Contribution

It provides new insights into the distinct effects of Cu doping on LiFeAs's lattice structure and electronic properties compared to Co/Ni doping.

Findings

Cu doping causes less lattice shrinkage than Co/Ni doping.

ARPES shows minimal change in Fermi surface sizes with Cu doping.

Cu doping results in little carrier doping effect at the Fermi surface.

Abstract

The Cu substitution effect on the superconductivity of LiFeAs has been studied in comparison with Co/Ni substitution. It is found that the shrinking rate of the lattice parameter c for Cu substitution is much smaller than that of Co/Ni substitution. This is in conjugation with the observation of ARPES that shows almost the same electron and hole Fermi surfaces (FSs) size for undoped and Cu substituted LiFeAs sample except for a very small hole band sinking below Fermi level with doping, indicating little doping effect at Fermi surface by Cu substitution, in sharp contrast to the much effective carrier doping effect by Ni or Co.