Structural, half-metallic magnetism and elastic properties of the KMnQ2 (Q=O, S, Se, Te) chalcogenides from first-principles calculations

• Some physical properties of the KMnQ2 (Q=O, S, Se, Te) compounds have been predicted.
• The considered crystals are soft materials and mechanically stable.
• The examined materials are found to be half-metallic.
• The magnetic moment is mainly originated from the transition metal Mn.

The structural, electronic, magnetic and elastic properties of the ternary chalcogenides KMnQ2 (Q=O, S, Se, Te) crystals were investigated by means of spin-polarized density functional theory calculations. The 3d orbitals of the Mn atoms were treated using the GGA+U approach. The calculated equilibrium structural parameters agree well with the experimental data. Based on the analysis of the spin-polarized band structures and density of states, we predict the half-metallic character of the studied compounds, with a half-metallic gap of 1.38 eV, 0.53 eV, 0.37 eV and 0.14 eV for KMnO2, KMnS2, KMnSe2 and KMnTe2, respectively, and a total magnetic moment of 4.00μB per unit-cell for all considered structures. The examined properties for the title compounds include also the single-crystal elastic constants, bulk modulus, shear modulus, Young's modulus and Poisson's ratio.