Competition between electronic correlations and hybridization in CaMn$_{2}$Bi$_{2}$

TL;DR

This study investigates the electronic structure of CaMn$_2$Bi$_2$, revealing the dominant role of magnetic correlations in its band gap and its relation to high-temperature superconductors, with implications for topological properties.

Contribution

The paper demonstrates that in CaMn$_2$Bi$_2$, magnetic correlations primarily control the band gap under pressure, highlighting its similarities to cuprates and pnictides and providing insights into its topological triviality.

Findings

Band gap governed by magnetic correlations under pressure

Hybridization influences higher energy states

CaMn$_2$Bi$_2$ is topologically trivial across studied pressures

Abstract

We study the interplay between electronic correlations and hybridization in the low-energy electronic structure of CaMn$_2$Bi$_2$, a candidate hybridization-gap semiconductor. Utilizing a DFT+$U$ approach we find both the antiferromagnetic N\'eel order and band gap in good agreement with the corresponding experimental values. We further find that, under hydrostatic pressure, the band gap is mainly governed by magnetic correlations, whereas hybridization has a greater impact on states at higher band energies. This result suggests that CaMn$_2$Bi$_2$ is more closely related to the high-temperature superconducting cuprates and iron pnictides than the heavy fermion class of materials. Finally, we also find the antiferromagnetic CaMn$_2$Bi$_2$ to be topologically trivial for all pressures studied.