Interfacial Spin Polarization and Magnetic Structure of Co/MgO/Co Magnetic Tunnel Junction: Ab Initio Calculation

Abstract

Using ab initio method based on the density functional theory, the equilibrium bcc-Co(001)/rocksalt-MgO(001)/bcc-Co(001) magnetic tunnel junction structure was investigated. Spin polarization and magnetic moment were calculated for each atomic slab in the equilibrium structure by spin dependent density of states analysis. Interfacial Co atoms showed significantly larger spin polarization of –88.3%, compared to the value of inner Co slabs, –82.3%, and bulk bcc Co, –82.1%. Interestingly, Mg and O atoms also showed induced spin polarizability ranged from –45.0% to –66.0%, except for O atoms in the centered slab of barrier layer, which showed relatively small polarization, –14.9%. Magnetic moments for the electrode Co atoms were calculated to be ∼1.74 μB with no significant variation across the electrode.