Two Quaternary Sulfides Rb 2 Cu 3 FeS 4 and Rb 2 Cu 3 MnS 4 Magnetic Interactions and Electrical Behavior

Abstract

The two quaternary transition metal chalcogenides Rb₂Cu₃MS₄ (M = Fe, Mn) are based on a common structural pattern consisting of two-dimensional (2D) arrangements of sulfur tetrahedra linked by edges, with the ThCr₂Si₂-type structure. They are prepared from alkali metal carbonate Rb₂CO₃ and transition metal oxides CuO, Fe₂O₃ or MnO by CS₂/Ar sulfurization at 850°C ≤ T ≤ 900°C. The magnetic susceptibilities are directly measured as a function of the temperature. Rb₂Cu₃MnS₄ presents a magnetic transition from a high spin (Mn²⁺) to the low spin state (µ_eff ≈ 1.5 µ_B), while the iron analog Rb₂Cu₃FeS₄ orders antiferromagnetically at T_N ≈ 6 K under an applied field of one kGauss.