The ultrafast dynamic of the magnetization in magnetic nanostructures is a key factor for designing news miniaturized electronic devices (e.g. magnetic memories, oscillators,?) . The use of new concepts like the injection of a spin polarized current requests a significant reduction of the size of the active part of the device. Achieving this size reduction requires expensive advanced fabrication techniques. In this context, the numerical modeling, by its predictive role, allows to establish easily the most convenient strategy to be followed for the device realization and also for a deeper understanding of the underlying physical mechanisms. This project will be focused on multilayer magnetic nanopillars. Several kinds of interaction are acting between the ferromagnetic layers (dipolar coupling, RKKY exchange, spin torque transfer, cpin-orbit coupling, spin HAll effect) with direct impact on the magnetic/electric response of the nanopillar. Pulses of polarized current will be injected combined with pulses of externally applied field. The main goal is to identify the optimal excitation for reducing the switching time and the energy consumption. Numerical studies will be carried out using micromagnetic solvers by varying several parameters (size, shape, materials,..) according to the experimental input information. The numerical tools are developed and shared between Spintec and the Institute Néel, CNRS, located at Grenoble too.