| Abstract Scope |
The motion of domain walls due to the spin torque generated by coherent coherent carrier transport [1] is of considerable interest for the development of spintronic devices [2]. We model two π Neel walls [3] separated by a variable distance, and calculate transport characteristics and spin torque through the system [4]. We model a realistic magnetization profile[5] for each π wall as a piecewise linear function, where the wavefunctions in each linearly varying segment can be solved analytically[6], and use transfer matrices to connect the segments. We find that for large separations, the domain walls show the resonant transmission behavior of a spin-dependent double barrier; for smaller separations, the transmission spectrum approaches that of a 2π wall of the same size as the double wall system. Similarly, the spin torque as a function of incident carrier energy shows several resonance peaks for larger separations between the two domain walls, and behavior more consistent with the 2π wall for smaller separations. The total spin torque across the system as a function of the separation between the π walls exhibits nonlinear behavior, with a peak at a particular separation, and then saturating for larger separations at a slightly lower value than at the peak. We find that the magnitude of this saturation spin torque is larger than both the equivalent torque for a 2π wall and the torque for two non-interacting π walls. This work is supported by an ARO MURI. |