We study the relationship between antiferromagnetic order and the electronic properties of ${\mathrm{KCuMnS}}_2$ with the ${\mathrm{ThCr}}_2{\mathrm{Si}}_2$-type structure. We propose two magnetic structures for ${\mathrm{KCuMnS}}_2$ with the ${\mathrm{ThCr}}_2{\mathrm{Si}}_2$-type structure. Powder samples of ${\mathrm{KCuMnS}}_2$ and ${\mathrm{KLiMnS}}_2$ were prepared for structural studies and magnetization measurements. In both compounds, the ${\mathrm{Mn}}^{2+}$ site is alloyed by either ${\mathrm{Cu}}^{+}$ or ${\mathrm{Li}}^{+}$. We also prepared single crystals of ${\mathrm{KCuMnS}}_2$ 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 ${\mathrm{KCuMnS}}_2$ exhibits long-range magnetic ordering with a Néel temperature near 160 K and a moment of 0.92(2) ${\mu }_B/{\mathrm{Mn}}^{2+}$ at 6 K. In contrast, ${\mathrm{KLiMnS}}_2$ 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 ${\mathrm{KCuMnS}}_2$ is semiconducting, there is an anomaly around the Néel temperature, which indicates that long-range magnetism influences its electronic structure.

• Received 22 October 2018
• Revised 6 April 2019

DOI:https://doi.org/10.1103/PhysRevMaterials.3.044411