Frustrated network of indirect exchange paths between tetrahedrally coordinated Co in Ba2CoO4

Abstract

We present the study of the electronic and magnetic interactions of Ba2CoO4, structurally unique because of the rare isolated CoO4 distorted tetrahedral coordination. We show that the Co(d)−O(p) hybridized states and 0.4 µB induced spin moment on O play roles in characterizing the existence of oxygen-hole states that stabilize Co in the high spin configuration with full degeneracy lifting by the distorted tetrahedra. The calculated isotropic exchange interaction parameters demonstrate the presence of 3D network of magnetic coupling and our results further provide proof for the indirect exchange mechanism mediated by O atoms via the Co−O• • • O−Co path.