Temperature-dependent properties of magnetic CuFeS₂ from first-principles calculations: Structure, mechanics, and thermodynamics

Chalcopyrite (CuFeS₂) is an antiferromagnetic semiconductor with promising magnetic and electrical properties, although these properties are not yet completely understood. The structural, magnetic, and electronic properties of bulk CuFeS₂ were studied via first-principles plane-wave pseudopotential calculations based on density functional theory (DFT) using DFT+U and hybrid functional B3LYP methodology. The temperature-dependent structural, thermal, and mechanical properties of tetragonal CuFeS₂ were also investigated via density functional perturbation theory. Furthermore, the structural parameters, elastic constants, bulk and shear moduli, volume expansion, and specific heats as a function of temperature were evaluated. Tetragonal CuFeS₂ was found to exhibit negative thermal expansion behavior at temperatures lower than 100 K. A comprehensive comparison of the various calculated parameters with earlier published studies is also presented along with available experimental data and used as a basis to critically discuss the various properties of CuFeS₂.