The stacking of antifluorite Fe2P2 layer on the electronic structure of the ternary compounds CaFe2P2, BaFe2P2 and EuFe2P2

This work reports a first-principle calculations as a comparative study of the electronic structural properties of the three related tetragonal compounds EuFe2P2, BaFe2P2 and CaFe2P2. The main trends of electronic band structure, density of states, and Fermi surface for the three compounds have been studied. The conventional cell mode contains two Fe-P layers; one at 0.375 and the other at 0.625 on the [0 0 1] axis, enclosing a layer of the rare-earth or alkaline earth atom at 0.5 (the origin is located at 4/mmm). It has been found that the replacement of Eu by either Ba or Ca produces a critical change in the magnetic properties. The calculations showed that the anion replacement of Eu → Ba → Ca has changed the interlayer spacing which has affected the electronic charge density and the magnetic moment. The resulted magnetic moment of the three compound EuFe2P2, BaFe2P2 and CaFe2P2 is 6.78, 0.0 and 1.2 μB respectively. The study of the three compounds has showed that the spin-orbit coupling in 4f compound EuFe2P2, with heavy Eu element, has a higher effect than the crystal field and vice versa in BaFe2P2 and CaFe2P2. The topology of the Fermi surface is mainly determined by the dispersion of Fe-d and P-p states, which explains the lack of either superconductivity or magnetic order of Fe in these compounds.