Exploring the structural, electronic, and magnetic properties of cation-ordered 3d-5d double-perovskite Bi2FeReO6 and Bi2FeIrO6 thin films from first principles

Abstract

We report a first-principles study of Bi-based 3d-5d ordered double-perovskite oxides (A2BB′O6) with a 3d atom (Fe) at the B site and 5d atoms (Re, Ir) at the B′ site while keeping highly polarizable ions (Bi3+) at the A site. We find that, under coherent heteroepitaxy, Bi2FeReO6 exhibits a strain-driven antiferromagnetic insulator to ferrimagnetic semimetal transition, while Bi2FeIrO6 shows a correlation driven ferromagnetic insulator to ferrimagnetic half-metal transition with calculated magnetic moments of 5 and 3μB/f.u., respectively. These properties along with the low band gaps in the insulating phases make the compounds appealing for spintronics applications. Furthermore, in Bi2FeIrO6, the conduction and valence states are localized on different transition metal sublattices implying more efficient electron-hole separation upon photoexcitation, a desirable feature for photovoltaic applications.