Insulating state and the importance of the spin-orbit coupling in Ca${}_3$CoRhO${}_6$

Abstract

We have carried out a comparative theoretical study of the electronic structure of the novel one-dimensional Ca${}_3$CoRhO${}_6$ and Ca${}_3$FeRhO${}_6$ systems. The insulating antiferromagnetic state for the Ca${}_3$FeRhO${}_6$ can be well explained by band structure calculations with the closed shell high-spin $d^5$ (Fe${}^{3+}$) and low-spin $t_{2g}^6$ (Rh${}^{3+}$) configurations. We found for the Ca${}_3$CoRhO${}_6$ that the Co has a strong tendency to be $d^7$ (Co${}^{2+}$) rather than $d^6$ (Co${}^{3+}$), and that there is an orbital degeneracy in the local Co electronic structure. We argue that it is the spin-orbit coupling which will lift this degeneracy thereby enabling local spin density approximation + Hubbard U (LSDA+U) band structure calculations to generate the band gap. We predict that the orbital contribution to the magnetic moment in Ca${}_3$CoRhO${}_6$ is substantial, i.e. significantly larger than 1 ${\mu }_B$ per formula unit. Moreover, we propose a model for the contrasting intra-chain magnetism in both materials.

7 pages, 4 figures, and 1 table

References in corpus (2)

• Valence, spin, and orbital state of the Co ions in the one-dimensional Ca3Co2O6: an x-ray absorption and magnetic circular dichroism study
• Nature of magnetism in Ca${}_3$Co${}_2$O${}_6$

Cited by in corpus (3)

• Ising magnetism and ferroelectricity in Ca${}_3$CoMnO${}_6$
• X-ray absorption and x-ray magnetic dichroism study on Ca3CoRhO6 and Ca3FeRhO6
• Structural effects on the spin-state transition in epitaxially strained LaCoO${}_3$ films