Abstract
The study of the electronic and magnetic structure of -FeS is based on a model which consists of iron surrounded by six S tetrahedra forming a cluster; its three-dimensional structure is based on x-ray diffraction data. For many-electron terms of ferrous high-spin compounds derived from semiempirical cluster calculations, we investigate spin-orbit coupling, electric field gradient (EFG), and susceptibility. In particular for the EFG we discuss valence, overlap, and lattice contributions. Within the paramagnetic region of -FeS we investigate the orientation of the EFG with respect to the crystallographic frame, the Mössbauer parameters and , and the susceptibility; we find our results in reasonable agreement with the recent experimental data of Wehner. Within the antiferromagnetic region at 4.2 K we study the influence of the molecular exchange field upon EFG, , and , and we further estimate the orientation of the internal magnetic field () at the iron nucleus with respect to the crystallographic frame. Finally we derive an angle of 27.7° between and the main component of the EFG. Our low-temperature study of -FeS agrees with the recent experimental findings of Wehner, but it disagrees with those of Ono and Ito.
- Received 27 March 1975
DOI:https://doi.org/10.1103/PhysRevB.12.3902
©1975 American Physical Society