Chirality reversal of vortices induced by surface acoustic waves

We study the magnetization state and chirality change in the vortex nucleated in the Py disk array in the presence of the surface acoustic wave (SAW) through experiments and simulations. When the magnetic field sweeps across the disk, the presence of the SAW fundamental frequency helps the magnetization to change easily from the buckling to the vortex state. While with the help of the third and fifth harmonics of the acoustic fundamental frequency, besides the changes in magnetic state, some vortices also change their chirality. The reason for this change is that the spin-vorticity coupling induced by the SAW leads to a change in the macroscopic magnetic moment through angular momentum transfer between the mechanical and electron spins. Considering the spin-vorticity coupling equivalent field, called the Barnett field, we simulate the whole process of a vortex under a magnetic field with the help of SAW. The results show that in the presence of a Barnett field, the initial nucleation position and the nucleation process of the vortex are changed, which in turn causes the vortex chirality to change. This work provides ideas for manipulating specific magnetization states and promoting the application of the topological magnetic structure.