Density functional study of BaNi$_2$As$_2$: Electronic structure, phonons and electron-phonon superconductivity

TL;DR

This study uses first principles calculations to analyze BaNi₂As₂'s electronic structure, phonons, and electron-phonon interactions, suggesting it is a conventional superconductor with potential magnetic influences.

Contribution

It provides a detailed first-principles analysis of BaNi₂As₂'s electronic and phononic properties, highlighting its classification as a phonon-mediated superconductor with possible magnetic effects.

Findings

BaNi₂As₂ has a Fermi surface distinct from BaFe₂As₂.

Results support conventional phonon-mediated superconductivity.

Potential influence of spin fluctuations due to proximity to magnetism.

Abstract

We investigate the properties of BaNi$_2$As$_2$ using first principles calculations. The band structure has a similar shape to that of the BaFe$_2$As$_2$, and in particular shows a pseudogap between a manifold of six heavy $d$ electron bands and four lighter $d$ bands, i.e. at an electron count of six $d$ electrons per Ni. However, unlike BaFe$_2$As$_2$, where the Fermi energy occurs at the bottom of the pseudogap, the two additional electrons per Ni in the Ni compound place the Fermi energy in the upper manifold. Thus BaNi$_2$As$_2$ has large Fermi surfaces very distinct from BaFe$_2$As$_2$. Results for the phonon spectrum and electron-phonon coupling are consistent with a classification of this material as a conventional phonon mediated superconductor although spin fluctuations and nearness to magnetism may be anticipated based on the value of $N(E_F)$.