First-principles study on structural, magnetic and electronic properties of EuFe2–<i>x</i>Ni<i>x</i>As2 solid solutions

The magnetic ground state and electronic structure properties of solid solutions EuFe2–xNixAs2 (x = 0, 0.08, 0.12, 0.20, 0.40, 2.0) are investigated using the full-potential linearized augmented-plane wave method. The results show that Ni substitution has a robust influence on the structural, magnetic ground state, and electronic properties of EuFe2As2. When 10% of Ni is substituted for the Fe atoms, orthorhombic-tetragonal distortion is observed. Simultaneously, as the Ni concentration increases, the density of states (DOS) at the Fermi level (EF) decreases implying that the electronic state becomes more stable. In alloys with x = 0.20, 0.40, the partial DOS of both Eu and Fe, as well as their strong spin polarization, show a dominant contribution around EF. For x &amp;gt; 0.12, there is a stronger interband scattering, as evidenced by a large number of electronic band crossing EF. The multi-sheet structure is revealed by the Fermi surface topologies in all compounds. The electron localization functions show metallic and covalent bonds in EuFe2As2, EuFe1.6Ni0.4As2, and EuNi2As2 with bonds in EuFe2As2 being the most covalent.