Abstract
We investigate the microscopic origin of the ferromagnetic and antiferromagnetic spin exchange couplings in the quasi-one-dimensional cobalt compound In particular, we establish a local model which stabilizes a ferromagnetic alignment of the spins on the cobalt sites with trigonal prismatic symmetry, for a sufficiently strong Hund’s rule coupling on the cobalt ions. The exchange is mediated through an cobalt ion at the octahedral sites of the chain structure. We present a strong coupling evaluation of the Heisenberg coupling between the Co spins on a separate chain. The chains are coupled antiferromagnetically through super-superexchange via short O-O bonds.
- Received 1 September 2003
DOI:https://doi.org/10.1103/PhysRevB.69.140405
©2004 American Physical Society