Simulation and Modeling of Racetrack Memories With VCMA Synchronization

The control of the motion of magnetic domains is of crucial interest for the development of several spintronic applications, such as high-density racetrack memories and domain wall logic. In these devices, the domain wall manipulation can be achieved via pulsed currents or applying an external field. However, real-world applications require accurate signal synchronization systems, keeping limited the power budget. Up to now, geometrical restrictions in the magnetic wire, known as notches, were used to confine domain walls at the expense of a higher current to depin the blocked information. The solution based on the Voltage Controlled Magnetic Anisotropy (VCMA) effect appears more promising because it has already been shown that this technology is able to effectively confine different magnetic textures, avoiding the need for strong depinning currents, and simplifying the fabrication process. The anisotropy variation induced by the VCMA can create barriers or wells that can be used to limit the movement of domain walls and obtain an effective synchronization. In our study, we propose a system-level evaluation of the effectiveness of the proposed VCMA synchronization methods. Our analysis is referred to a stack of CoFeB/MgO. Starting from a two-coordinates model, the motion of domain walls, the performance and the efficiency of the approach is evaluated. The VCMA proved to be comparable with respect to the notch synchronization approach in terms of energetic performance with a clear advantage in the control and the realization at the system level.