[formula omitted] A novel antiferromagnetic rare-earth polychalcogenide

The reaction of Eu with a molten mixture of [formula omitted] and excess Se has produced a new rare earth dichalcogenide, [formula omitted] with a type “a” antiferromagnetic structure. The compound crystallizes in the tetragonal space group [formula omitted] forming into small single crystal rectangular blocks with their long axis along c. The high temperature magnetic susceptibility exhibits Curie–Weiss behavior with a ferromagnetic [formula omitted] and an effective moment [formula omitted] magnetons consistent with the theoretical value of 7.94 for the [formula omitted] free ion. There is a peak in [formula omitted] at [formula omitted] which is attributed to an antiferromagnetic transition. At [formula omitted] with the magnetic field, H, applied along c, [formula omitted] exhibits a sharp increase near 1.5 T attributed to a metamagnetic transition. With H along a the moments saturate at about 5 T. A simple mean field model in which the Eu ions in the ab plane are coupled into ferromagnetic sheets, with alternate sheets along c coupled antiferromagnetically to form a bulk antiferromagnet is used to interpret the data.