Micromagnetic Study of Dipole-Field-Mediated Synchronization Between Domain Wall Spin Torque Nano-Oscillators

Spin torque nano-oscillators (STNOs) exhibiting low power of microwaves generated from a single device have to be bundled and phase-locked to achieve levels of emission that are satisfactory for applications. In this paper, dipolar coupling and synchronization in the ensembles of nanowire-shaped domain wall STNOs are investigated with the micromagnetic modeling method. The stray field interaction facilitates synchronization in pairs of nanowires despite differences in their diameters, provided separation of nanowires is below some threshold value. With proper positional arrangement, the synchronization can be extended onto larger sets, even though dipolar coupling is significant only between the immediately adjacent oscillators.