Magnetotransport Properties in Fe/MgO/Fe Magnetic Tunnel Junction: DFT+JunPy+LLG Calculation*

Our self-developed “JunPy” package has successfully combined the self-consistent Hamiltonian by using the first-principles calculation with the non- equilibrium Green’s function (NEGF) method to calculate the noncollinear spin torque effect in the nm-scale magnetic heterojunctions [1]. The divide-and-conquer (DC) method was first applied to reveal the oscillatory decay of layer-resolved spin torques away from the MgO/Fe interface, and suggests a very thin Fe layer thickness below 2 nm to preserve the efficient current-driven magnetization switching [2]. On the other hand, we include the spin-orbit coupling (SOC) in the first-principles calculation to study the MgO/Fe interfacial magnetic anisotropy (IMA), and obtain the spin torque caused by the anisotropy field. By employing the Landau-Lifshitz-Gilbert (LLG) equation, we study the macroscope magnetization switching in Fe/MgO/Fe magnetic tunnel junction including the influences of current-driven spin torque and interfacial anisotropy field. The calculated resistance as a function of magnetic field (R-H loop) and of bias (R-V loop) are thus obtained and well comparable with experimental results.

[1] Y. -H. Tang and B. -H. Huang, Phys. Rev. Research, 3, 033264 (2021). 

[2] B. -H. Huang et al., AIP Advances 11, 015036 (2021).