Expansion research on half-metallic materials in double perovskites of Sr2BB′O6 (B = Co, Cu, and Ni; B′ = Mo, W, Tc, and Re; and BB′ = FeTc)

Abstract

Calculations with full structural optimization were conducted by generalized gradient approximation (GGA) with correlation effect correction (GGA+U) based on density functional theory. The stable structures, magnetic stable phases, and electronic structures of the double perovskites of Sr2BB′O6 (B=Co, Cu, and Ni; B′=Mo, W, Tc, and Re; and BB′=FeTc) were investigated. All compounds, except for Sr2NiMoO6 and Sr2NiWO6, can be half-metallic (HM) materials in the GGA scheme; Sr2NiMoO6 and Sr2NiWO6 are ferromagnetic (FM) insulators. Sr2FeTcO6, Sr2CoWO6, and Sr2NiTcO6 are stable ferrimagnetic (FiM)–HM compounds in the GGA and GGA+U schemes. Given the small energy difference between their antiferromagnetic and FiM states, Sr2CoTcO6, Sr2CuMoO6, Sr2NiMoO6, Sr2NiWO6, and Sr2NiReO6 can coexist. The mechanisms of the HM–FiM properties can be described by d–d′ hybridization with double-exchange interaction.