Thickness dependence of spin torque effect in Fe/MgO/Fe magnetic tunnel junction: Implementation of divide-and-conquer with first-principles calculation

In this study, we develop a divide-and-conquer (DC) method under the framework of first-principles calculation to prevent directly solving Hamiltonian of a large device with time-consuming self-consistent process. The DC implementation combined with JunPy package reveals 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 switch. This newly developed JunPy-DC calculation may efficiently resolve current self-consistent difficulties in noncollinear spin torque effects for novel spintronic applications with complex magnetic heterostructures.