Site-selective electronic structure of pure and doped Ca2O3Fe3S2

Using density functional dynamical mean-field theory we investigate the site-selective electronic structure of Ca2O3Fe3S2. We confirm that the parent compound with two distinct iron sites is a multiorbital Mott insulator similar to La2O3Fe2S2. Upon electron/hole doping, carrier localization is found to persist in the two active iron channels because the chemical potential lies in a gap structure with anisotropic and almost vanishing states near the Fermi energy. This emergent behavior stems from large electronic reconstruction caused by dynamical spectral weight transfer involving states with distinct d-shell occupancies and orbital character at low energies. We detail the implications of our microscopic analysis and discuss the underlying physics which will emerge in future experiments on Ca2O3Fe3S2.