Angle-Resolved Photoemission Spectroscopy Study of BaCo2As2

TL;DR

This study uses ARPES and calculations to analyze the electronic structure of BaCo2As2, revealing differences from FeAs-based superconductors and showing a rigid band shift due to Co substitution.

Contribution

It provides detailed experimental and theoretical insights into the Fermi surface and band structure of BaCo2As2, highlighting the effects of Co substitution compared to Fe-based compounds.

Findings

Absence of nesting between electron and hole Fermi surface pockets.

Fermi surface topology consistent with calculations.

Rigid shift of the Fermi energy due to Co substitution.

Abstract

We use angle-resolved photoemission spectroscopy and full-potential linearized augmented-plane-wave (FP-LAPW) calculations to study the electronic structure of BaCo2As2. The Fermi surface (FS) maps and the corresponding band dispersion data (at 90 K and 200 K) reveal a small electron pocket at the center and a large electron pocket at the corner of the Brillouin zone. Therefore the nesting between electron and hole FS pockets is absent in this compound, in contrast to the parent compounds of FeAs-based high-T_c superconductors. The electronic structure at about 500 meV binding energy is very similar to features at the chemical potential in BaFe2As2. This indicates that complete substitution of Co for Fe causes a nearly rigid shift in the Fermi energy by adding two electrons per formula unit without significant changes in the band dispersions. The experimental FS topology as well as band dispersion data are in reasonable agreement with the FP-LAPW calculations.