Comprehensive Modeling of Coupled Spin and Charge Transport through Magnetic Tunnel Junctions

A drift-diffusion approach to coupled spin and charge transport has been commonly applied to determine the spin-transfer torque acting on the magnetization in metallic valves. This approach, however, is not suitable to describe the predominant tunnel transport in magnetic tunnel junctions. Here we demonstrate that by introducing a magnetization dependent resistivity and adjusting the spin diffusion coefficient one can successfully apply the generalized spin and charge drift-diffusion approach also to magnetic tunnel junctions. As a unique set of equations is used for the entire structure, this paves the way to develop an efficient finite element based approach to describe the magnetization dynamics in emerging spin-transfer torque memories.