We present first-principles based calculations of electronic structures and tunneling conductance of Co2 YZ/MgO (∼2 nm) / Co2 YZ (001) (YZ=MnSi,CrAl) magnetic tunnel junctions (MTJs). It is found that YZ (MnSi and CrAl)-terminated interfaces are thermodynamically stable as compared with Co-terminated interfaces in Co2 YZ/MgO (001) junctions. In the CrAl-termination, no interface states appear in both sides of the junctions, preserving the half metallicity of Co2 CrAl, while reduction of the spin polarization is significant in the MnSi termination. Co2 CrAl, however, has no Δ1 band at the Fermi level, thus the majority-spin conductance of Co2 CrAl/MgO/ Co2 CrAl (001) MTJs in the parallel magnetization is much smaller than that of Co2 MnSi/MgO/ Co2 MnSi (001) MTJs. We propose that MTJs having an ultrathin Co2 CrAl layer between Co2 MnSi electrode and MgO barrier, i.e., Co2 MnSi/ Co2 CrAl/MgO (001) junctions, can derive both the half-metallic character at the interface and the large tunneling conductance through the Δ1 channel in the parallel magnetization.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2008 Aug 18|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics