We have employed first principles calculations to study the electronic structure and magnetic properties of the low-dimensional phosphates, and . Using the self-consistent tight-binding linearized muffin-tin orbital method and the order muffin-tin orbital method, we have calculated the various intrachain as well as the interchain hopping parameters between the magnetic ions for both the compounds. We find that the nearest-neighbor intrachain hopping is the dominant interaction suggesting the compounds to be indeed one dimensional. Our analysis of the band dispersion, orbital projected band structures, and the hopping parameters confirms that the super-super exchange interaction takes place along the crystallographic direction mediated by O-P-O. We have also analyzed in detail the origin of short-range exchange interaction for these systems. Our ab initio estimate of the ratio of the exchange interaction of to that of compares excellently with available experimental results.
- Received 7 May 2007
©2007 American Physical Society