Switching of skyrmioniums induced by oscillating magnetic field pulses

Skyrmioniums are exotic magnetic configurations that have several potential applications, as devices for magnetic recording, in Spintronics. In this work, using micromagnetic simulation, we show that it is possible to switch a skyrmionium in an isolated nanodisk. First, we have obtained the ground state of the nanodisk for a fixed value of perpendicular anisotropy constant K_z and for several values of Dzyaloshinskii-Moriya exchange constant D_int. Next, in order to obtain the frequencies of the spin wave mode, we have calculated the power spectrum of the fluctuations of the spatial z-component of the magnetization for values of D_int where the ground state of nanodisk is a skyrmionium. Our results show that applying oscillating perpendicular magnetic field pulses with a frequency equal to that of the spin wave mode, and tuning the values of the intensity of the applied magnetic field and its duration in the sub-nanosecond range, one can switch the polarity of the skyrmionium in the nanodisk. We have also obtained, from the micromagnetic simulation of the process of inversion of polarity of the skyrmioniums, the several intermediate magnetic configurations of the nanodisk, revealing the full complexity of this phenomenon.