First-Principles Calculations of the Structure and Magnetic Phases of FeAs2 Compound under Pressure

O. Sebaa , 

Y. Zaoui, 

K. O. Obodo, 

H. Bendaoud, 

L. Beldi and 

B. Bouhafs

*Modeling and Simulation in Materials Science Laboratory Department of Physics Djillali Liabe s University of Sidi Bel-Abbe s Sidi Bel-Abbe s 22000, Algeria

 † Department of Physics University of South Africa Pretoria 0001, South Africa ‡ obodokingsley@gmail.com

Abstract

Understanding of different magnetic configurations for the FeAs2 iron pnictide compound is carried out using first-principles studies based on spin density functional theory (DFT) within the generalized gradient approximation (GGA), including the spin–orbit coupling (SOC). The calculated stable phase is in the marcasite (Pnnm) with nonmagnetic spin-ordering. We find that the FeAs2 compound in the nonmagnetic (NM) marcasite phase undergoes pressure-induced phase transition to the antiferromagnetic (AFM1) marcasite phase at 12$$GPa, then to the AFM CuAl2 (I$I$4/mcm) phase at 63$$GPa. The phase transition is also accompanied by semiconducting (marcasite phase) to metallic (CuAl2 phase) transition. The calculated electronic density of states profile shows the hybridization of the Fe-3d$d$ and As-4p$p$ orbitals plays an important role in determining the electronic and magnetic characters of this compound. The associated phase transition results in increased Fe-3d orbitals around the Fermi energy level.

https://sci-hub.tw/https://doi.org/10.1142/S2010324718500169