Correlation effects in the electronic structure of the Ni-based superconducting KNi2S2

TL;DR

This study uses advanced computational methods to explore how electron correlations influence the electronic structure and superconducting properties of KNi2S2, revealing significant mass enhancement and complex Fermi surface features.

Contribution

It introduces a combined LDA and Gutzwiller approach to analyze correlation effects in Ni-based superconductor KNi2S2, highlighting new electronic structure insights.

Findings

Correlation effects cause mass enhancement in KNi2S2.

Three energy bands cross the Fermi level due to correlations.

Mass enhancement persists across doping levels.

Abstract

The LDA plus Gutzwiller variational method is used to investigate the groundstate physical properties of the newly discovered superconducting KNi2S2. Five Ni-3d Wannier-orbital basis are constructed by the density-functional theory, to combine with local Coulomb interaction to describe the normal state electronic structure of Ni-based superconductor. The band structure and the mass enhanced are studied based on a multiorbital Hubbard model by using Gutzwiller approximation method. Our results indicate that the correlation effects lead to the mass enhancement of KNi2S2. Different from the band structure calculated from the LDA results, there are three energy bands across the Fermi level along the X-Z line due to the existence of the correlation effects, which induces a very complicated Fermi surface along the X-Z line. We have also investigated the variation of the quasi-particle weight factor with the hole or electron doping and found that the mass enhancement character has been maintained with the doping.