Importance of non-local electron correlations in BaNiS$_{2}$ semimetal from quantum oscillations studies

TL;DR

This study reveals the critical role of non-local electron correlations in BaNiS$_{2}$, a 3d semimetal, through quantum oscillations and advanced ab initio calculations, highlighting the importance of hybrid functionals with screened exchange.

Contribution

It demonstrates that including screened exchange in density functional theory is essential to accurately describe the Fermi surface of BaNiS$_{2}$, emphasizing the significance of non-local correlations.

Findings

Quasi-two-dimensional Fermi surface with Dirac bands

Modified HSE functional with 7% exact exchange best matches experiments

Non-local screened-exchange interactions are crucial in BaNiS$_{2}$

Abstract

By means of Shubnikov-de-Haas and de-Haas-van-Alphen oscillations, and ab initio calculations, we have studied the Fermi surface of high-quality BaNiS$_2$ single crystals, with mean free path $l \sim 400 ~\text{\AA}$. The angle and temperature dependence of quantum oscillations indicates a quasi-two-dimensional Fermi surface, made of an electron-like tube centred at $\Gamma$, and of 4 hole-like cones, generated by Dirac bands, weakly dispersive in the out-of-plane direction. Ab initio electronic structure calculations, in the density functional theory framework, show that the inclusion of screened exchange is necessary to account for the experimental Fermi pockets. Therefore, the choice of the functional becomes crucial. A modified HSE hybrid functional with 7% of exact exchange outperforms both GGA and GGA+U density functionals, signalling the importance of non-local screened-exchange interactions in BaNiS$_2$, and, more generally, in $3d$ compensated semimetals.