While CaFeO3 exhibits upon cooling a metal-insulator transition linked to charge ordering, SrFeO3 and BaFeO3 keep metallic behaviors down to very low temperatures. Moreover, alkaline-earth ferrites do not seem prone to orbital ordering in spite of the d4 formal occupancy of Fe4+. Here, from first-principles simulations, we show that the metal-insulator transition of CaFeO3 is structurally triggered by oxygen rotation motions as in rare-earth nickelates. This not only further clarifies why SrFeO3 and BaFeO3 remain metallic but allows us to predict that an insulating charge-ordered phase can be induced in SrFeO3 from appropriate engineering of oxygen rotation motions. Going further, we unveil the possibility to switch from the usual charge-ordered to an orbital-ordered insulating ground state under moderate tensile strain in CaFeO3 thin films. We rationalize the competition between charge and orbital orderings, highlighting alternative possible strategies to produce such a change of ground state, also relevant to manganite and nickelate compounds.
@article{arxiv.1804.07584,
title = {From Charge to Orbital Ordered Metal-Insulator Transition in Alkaline-Earth Ferrites},
author = {Mr. Yajun Zhang and Mr. Michael Schmitt and Mr. Alain Mercy and Prof. Philippe Ghosez and Prof. Jie Wang},
journal= {arXiv preprint arXiv:1804.07584},
year = {2018}
}