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

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 4.00 mu(B) 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. (C) 2016 Elsevier B.V. All rights reserved.