Density functional theory study of energetics, local chemical environment and magnetic properties in a high-entropic MnNiSi0.2Ge0.2Sn0.2Al0.2Ga0.2 intermetallic magnet

Abstract

Rare-earth-free magnetostructural MnNiSi-based solid solutions are considered as promising candidates for solid-state cooling applications. In this paper, we use density functional theory calculations to study the energetics, variations in atomic displacements and bond length, and magnetic properties of high-entropic, intermetallic MnNi-X (X = Si _0.2 Ge _0.2 Sn _0.2 Al _0.2 Ga _0.2 ) magnet in both the low-symmetry Pnma and high-symmetry $P6_3/mmc$ structures, where we confine the large configurational entropy to the non-magnetic X-site of the compound. Our calculations reveal that the high-entropic chemical substitution of Si _0.2 Ge _0.2 Sn _0.2 Al _0.2 Ga _0.2 in the X-site carry fingerprints that favor a reduction in magnetostructural transition temperature with minimal impact of total magnetization. These results motivate a promising path of high-entropic X-site substitutions to tune the magnetostructural properties of MnNiSi-based solid solutions.

Keywords

• high-entropy materials
• intermetallic magnets
• multicaloric materials
• density functional theory
• solid-state cooling