Exchange interactions in the quasi-linear-chain antiferromagnetKFeS2

A. Mauger, M. Escorne, C. A. Taft, N. C. Furtado, Z. P. Arguello, T. P. Arsenio
1984 Physical Review B (Condensed Matter)  
We report magnetic susceptibility measurements on KFeS2 in the temperature range 4.2 & T & 300 K. In addition to a curvature of the susceptibility curve P(T) near 250 K, we also observe a small sharp maximum at 12.5 K characteristic of linear-chain antiferromagnetism in quasi-onedimensional systems. The results were interpreted with use of the molecular-field approximation and the temperature-dependent Green's-function method as well as the refined molecular-field theory for the Heisenberg
more » ... . The interchain, and intrachain exchange interactions and their ratio (g=10 ) which measures the one dimensionality of the system could be estimated and compared with other results. We attribute the positive value of the paramagnetic Curie temperature 8-+70 K to a ferromagnetic exchange interaction J2 between next-nearest neighbors along the chains, superimposed on the antiferromagnetic exchange Jl between nearest neighbors. The best fit to the experimental data is obtained for Jl/k~-23. 6 K, J2/k& --41.9 K, and J'/k& --3.3 K, with J being the interchain exchange constant. We suggest that the three-dimensional antiferromagnetism occurs at the Neel temperature T~-12.5 K rather than at 250 K as is usually assumed.
doi:10.1103/physrevb.30.5300 fatcat:fjn3izsstfaafmimkoh5hcnnje