Ab initio calculations of structural and magnetic properties of Fe(001)/MgO(001)/Fe(001) magnetic tunnel junction with interfacial Mg vacancy

The structural and magnetic properties of the Fe(0 0 1)/MgO(0 0 1)/Fe(0 0 1) magnetic tunnel junction (MTJ) with Mg vacancy at the interface were investigated using density functional theory. For a defect-free MTJ, the interfacial Fe-O distance was 2.06 angstrom and 13.8% of thickness reduction was found in electrode layers. For the Mg deficient MTJ system, the interfacial Mg atoms were positioned 0.19 angstrom below the O-interface atoms, resulting in the Fe-Mg distance of 1.74 angstrom. Each atomic slab exhibited large fluctuations of spin polarization values since complex slab separation occurred in both barrier and electrode layers. Specifically, the magnetic moment of 0.20 mu B was induced for O atoms at the interface slab. Large variations in the spin polarization and magnetic moment values for Fe atoms were found in the MTJ system with Mg vacancy.This work was supported by the Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea Government (MOST) (No R01-2007-000-10537-0)