Correlation versus hybridization gap in CaMn ₂ Bi ₂

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. By employing a DFT+U approach we find both the antiferromagnetic Néel order and band gap in good agreement with the corresponding experimental values. Under hydrostatic pressure, we find a crossover from hybridization gap to charge-transfer insulting physics due to the delicate balance of hybridization and correlations. Increasing the pressure above P_c= 4 GPa we find a simultaneous pressure-induced volume collapse, plane-to-chain, insulator to metal transition. Finally, we have also analyzed the topology in the antiferromagnetic CaMn ₂ Bi ₂ for all pressures studied.