Study of elastic, structural, electronic, magnetic, and topological properties of η-Fe2C carbide under pressure

Abstract

This paper studies the elastic, structural, electronic, magnetic, and topological properties of the η-Fe2C carbide under pressure by resorting to DFT-GGA's first principle via FPLAPW-WIEN2K and ElaStic1.0 software. Properties were calculated for strain vectors and pressures shown to maintain the orthorhombic structure of the carbide. Electronic bands, Fermi surfaces, and electron states are slightly distorted in the direction of the strain vector considered. The density of states, dominated by the 3d electrons of Fe, and to a lesser extent, by the 2p electrons of C, is lower in the pressure-borne compressed state than in the expanded one, a degree of hybridization existing between these states in certain energy regions, in tandem with a more extended first Brillouin zone and a higher Fermi level, which translates into greater structural stability in the latter state. The resulting magnetic anisotropy is a consequence of the difference in density of states between the spin-up and spin-down configurations, mainly in the orbitals of the aforesaid electrons. The pressure was also found to affect the number of bond, ring, and cage critical points (CP) found, as well as their distance from the atom.