Magnetic field, current and voltage-induced ferromagnetic resonance in magnetic tunnel junctions: Micromagnetic spatial analysis

For understanding physical mechanisms occurring in ferromagnetic nano-layers, micromagnetic simulations are commonly used. In order to perform an advanced analysis of complex magnetization dynamics induced by phenomena such as Spin-Transfer-Torque (STT) [1,2] or voltage-controlled anisotropy [3,4] changes, a spatial distribution of power spectral density is often needed [5]. We use a specially designed open-source tool for creating spectral density maps directly from a set of subsequent magnetization files [6], an output typically available in micromagnetic simulations [7]. By investigating multiple frequencies and areas, oscillation modes and nodes of spin waves can be precisely localized. In this work we discuss a ferromagnetic resonance in Magnetic Tunnel Junctions (MTJs). The Fast Fourier Transform (FFT) can be computed once for the whole oscillator, which produces a single distribution consistent with experimental results. However, in such case the information about the localization of magnetization oscillations modes of is lost.