Magnetic ground state of orthorhombically distorted CaCoO3 perovskite oxide: GGA and GGA+U calculations

Cobalt-based perovskite oxides have been attracted considerable attention due to their fascinating properties, especially entangled magnetic spin structures. Here, we comprehensively study the various magnetic ordering in recently reported orthorhombically distorted CaCoO3 perovskite oxide by employing the density functional theory calculations. A strong ferromagnetic coupling due to double exchange interactions between neighbouring Co atoms within the CoO2 bilayers is found than the anti-ferromagnetic coupling, which results in ferromagnetic spin ordering as a magnetic ground state with metallic electronic ground state (even Co is in its +4 state) for both exchange-correlation potentials (generalized gradient approximation (GGA) and GGA+U). The estimated magnetic transition temperature TC = 116/139 K for GGA/GGA+U, which is close to the experimentally observed value of 95 K for helimagnetic ground state.