Electronic Band Structure ofBaCo2As2: A Fully Doped Ferropnictide Analog with Reduced Electronic Correlations

Abstract

We report an investigation with angle-resolved photoemission spectroscopy of the Fermi surface and electronic band structure of ${\mathrm{BaCo}}_2{\mathrm{As}}_2$. Although its quasinesting-free Fermi surface differs drastically from that of its Fe-pnictide cousins, we show that the ${\mathrm{BaCo}}_2{\mathrm{As}}_2$ system can be used as an approximation to the bare unoccupied band structure of the related ${\mathrm{BaFe}}_{2-x}{\mathrm{Co}}_x{\mathrm{As}}_2$ and ${\mathrm{Ba}}_{1-x}{\mathrm{K}}_x{\mathrm{Fe}}_2{\mathrm{As}}_2$ compounds. However, our experimental results, in agreement with dynamical-mean-field-theory calculations, indicate that electronic correlations are much less important in ${\mathrm{BaCo}}_2{\mathrm{As}}_2$ than in the ferropnictides. Our findings suggest that this effect is due to the increased filling of the electronic $3d$ shell in the presence of significant Hund’s exchange coupling.