Tunneling magnetoresistance in Fe₃Si/MgO/Fe₃Si(001) magnetic tunnel junctions

We present a theoretical study of the tunneling magnetoresistance (TMR) and spin-polarized transport in Fe₃Si/MgO/Fe₃Si(001) magnetic tunnel junction (MTJ). It is found that the spin-polarized conductance and bias-dependent TMR ratios are rather sensitive to the structure of Fe ₃Si electrode. From the symmetry analysis of the band structures, we found that there is no spin-polarized Δ1 symmetry bands crossing the Fermi level for the cubic Fe₃Si. In contrast, the tetragonal Fe ₃Si driven by in-plane strain reveals half-metal nature in terms of Δ1 state. The giant TMR ratios are predicted for both MTJs with cubic and tetragonal Fe₃Si electrodes under zero bias. However, the giant TMR ratio resulting from interface resonant transmission for the former decreases rapidly with the bias. For the latter, the giant TMR ratio can maintain up to larger bias due to coherent transmission through the majority-spin Δ1 channel.