Theoretical investigations on the magnetic properties of the (Sc,Nb)Fe2 compounds

The theoretical investigations on the electronic and magnetic properties of the Sc 1-x Nb x Fe 2 (x = 0–0.6) Laves type intermetallic compounds with the C14 MgZn 2 -type structure are presented. The magnetic properties are determined by Fe 6h atoms forming two Kagomé hexagonal sublattices, separated by Fe 2a sites and Nb/Sc atoms in the interstices. ScFe 2 is a ferromagnet, but Nb for Sc substitution reduces interatomic distances and promotes antiferromagnetic interaction between Fe spins. The present theoretical study may provide an insight into the influence of the chemical composition and interatomic spacing on the magnetic properties (magnetic moments, exchange-coupling parameters, and Curie temperatures) of the Sc 1-x Nb x Fe 2 series of compounds. The spin-polarized fully relativistic Korringa-Kohn-Rostoker (SPR-KKR) band structure method has been employed, using the coherent potential approximation (CPA) to deal with substitutional disorder. The available experimental data are used to give a more comprehensive description of the electronic and magnetic properties. • For x ≥ 0.5, Sc₁-xNbₓFe₂ alloys show lower energy for ferrimagnetic vs. ferromagnetic spin structure. • Ferrimagnetic structure better explains steep magnetization drop for x > 0.3 in Sc₁₋ₓNbₓFe₂. • Exchange-coupling dependence on spin spacing drives ferro- to ferrimagnetic transition via volume shrinkage. • Volume-dependent spin ground state supports Nb substitution affecting magnetic order in Sc₁₋ₓNbₓFe₂ alloys.