Abstract
We study the relationship between antiferromagnetic order and the electronic properties of KCuMnS2 with the ThCr2Si2-type structure. We propose two magnetic structures for KCuMnS2 with the ThCr2Si2-type structure. Powder samples of KCuMnS2 and KLiMnS2 were prepared for structural studies and magnetization measurements. In both compounds, the Mn2+ site is alloyed by either Cu+ or Li+. We also prepared single crystals of KCuMnS2 for x-ray and neutron-diffraction studies and resistivity measurements. We relate these properties to the electronic structure calculated with density functional theory. Neutron-diffraction studies reveal that KCuMnS2 exhibits long-range magnetic ordering with a Néel temperature near 160 K and a moment of 0.92(2) μB/Mn2+ at 6 K. In contrast, KLiMnS2 never exhibits long-range magnetic ordering down to 3.5 K. Both sulfides never display a crystallographic phase transition from our temperature-dependent x-ray and neutron-diffraction studies. We discuss the magnetic phases in detail and how they relate to isostructural phases such as iron-based superconductors and related chalcogenides. Electrical resistance measurements indicate that while KCuMnS2 is semiconducting, there is an anomaly around the Néel temperature, which indicates that long-range magnetism influences its electronic structure.
