Control of Magnetization Precession Frequency Using Current Density of Spin-Orbit Torque Applied to Local Area

We numerically study current density dependence of magnetization dynamics in a local area induced by the spin-orbit torque as a source of spin waves. The precession frequency of magnetization dynamics shows large change at a critical current density, which controls the wave length of spin waves. The origin of the change is due to the increase of exchange field caused by the magnetization torsion at the interface between SOT-applied and non-applied regions. Our new finding gives a way to manipulate spin wave’s properties by controlling the magnetization direction in a local area.