First principles investigation of electronic and magnetic - propertiess of double perovskites A2NRuO6 (A2=Ba2, BaLa; N=V, Cr and Fe)

Abstract

The electronic and magnetic properties of double perovskites A₂NRuO₆ (A₂ = Ba₂, BaLa; N = V, Cr, Fe) have been investigated using the first-principles density-functional theory (DFT) within the generalized gradient approximation (GGA) and GGA+U schemes. All compounds of (A₂ = Ba²⁺) and doped (A₂ = Ba²⁺La³⁺) crystallize in a cubic structure with (Fm-3m) space group. The GGA results of (A₂ = Ba²⁺) predict half-metallic (HM), semiconductor and metallic character when (N = V, Cr, Fe), respectively which are completely stabilize at the HM nature within (A₂ = Ba²⁺La³⁺) compounds. By including the exchange-correlation energy in GGA+U scheme, all compounds show a HM property, except for Ba₂FeRuO₆ which appears as an insulating material. In addition, GGGA and GGA+U calculations of spin magnetic moments suggest a ferrimagnetic (FI) character for A₂NRuO₆ (N = V and Cr), switch to a ferromagnetic (FM) nature when N = Fe. It is found that the two ions of N³⁺– Ru⁵⁺ (A₂ = Ba₂) and N³⁺– Ru⁴⁺ (A₂ = BaLa) are governed by the antiferromagnetic interactions N³⁺ (3d)–O^2– (2p)–Ru⁵⁺∕ Ru⁴⁺ (4d) in high∕ low spin magnetic moments states.