Spinel oxides: Δ1 spin-filter barrier for a class of magnetic tunnel junctions

Abstract

The orbital composition of the electrode wave functions and the complex bands within the barrier band gap are two important factors in deciding the spin-filter effect. This is illustrated in a class of spinel oxides, including MgAl2O4, ZnAl2O4, SiMg2O4, and SiZn2O4. Through first-principles calculations of the complex bands and electron transmission along the [001] direction, they are shown to have the same Δ1 spin-filter effect as MgO due to the combination of both factors. Due to better lattice match with typical bcc magnetic electrodes than MgO, these materials provide a broad spectrum of candidate materials for magnetic tunnel junctions.