Nonlinear Behavior and Mode Coupling in Spin-Transfer Nano-Oscillators

Spin-transfer nano-oscillators (STNOs) are promising candidates for integrated spintronic microwave devices but improving their spectral coherence remains a key issue for applications. The authors have constructed multilayered nanopillars for harnessing the nonlinearity of the collective oscillation modes associated with two dipole-coupled vortices that in turn permits the properties of the collective modes (i.e. frequency and linewidth) to be tuned precisely. This is a crucial issue for applications as it can greatly improve the quality factor of these new types of nanoscale oscillators.