Angle-resolved spectroscopy study of Ni-based superconductor SrNi$_2$As$_2$

TL;DR

This study uses angle-resolved photoemission spectroscopy to investigate the electronic structure of SrNi$_2$As$_2$, revealing poor Fermi surface nesting and confirming Hund's exchange influence on electronic correlations.

Contribution

It provides detailed experimental electronic band structure data for SrNi$_2$As$_2$ and compares it with first-principles calculations, highlighting the role of Hund's coupling and 3d filling.

Findings

Poor nesting conditions observed in Fermi surface pockets

Experimental band structure agrees with calculations after slight renormalization

Highlights Hund's exchange as a key factor in electronic correlations

Abstract

We performed an angle-resolved photoemission spectroscopy study of the Ni-based superconductor SrNi$_2$As$_2$. Electron and hole Fermi surface pockets are observed, but their different shapes and sizes lead to very poor nesting conditions. The experimental electronic band structure of SrNi$_2$As$_2$ is in good agreement with first-principles calculations after a slight renormalization (by a factor 1.1), confirming the picture of Hund's exchange-dominated electronic correlations decreasing with increasing filling of the $3d$ shell in the Fe-, Co- and Ni-based compounds. These findings emphasize the importance of Hund's coupling and $3d$-orbital filling as key tuning parameters of electronic correlations in transition metal pnictides.