Exploring the structural , electronic and magnetic properties of cation ordered 3d-5d double perovskite Bi${}_2$FeReO${}_6$ and Bi${}_2$FeIrO${}_6$ thin-films from first-principles

Abstract

We report a first-principles study of Bi-based 3$d$-5$d$ ordered double perovskite oxides (A${}_2$BB${}^{\prime }$O${}_6$) with a 3$d$ atom (Fe) at the B-site and 5$d$ atoms (Re,Ir) at the B${}^{\prime }$-site while keeping highly polarizable ions (Bi${}^{3+}$) at the A-site. We find that, under coherent heteroepitaxy, Bi${}_2$FeReO${}_6$} exhibits a strain-driven anti-ferromagnetic insulator to ferrimagnetic semi-metal transition, while Bi${}_2$FeIrO${}_6$ shows correlation driven ferromagnetic insulator to ferrimagnetic half-metal transition with calculated magnetic moments of 5 ${\mu }_B$/f.u. and 3 ${\mu }_B$/f.u., respectively. These properties along with the low band gaps in the insulating phases make the compounds appealing for spintronics applications. Furthermore, in Bi${}_2$FeIrO${}_6$, 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.

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