Skyrmions Based Spin-Torque Nano-Oscillator

We present a model for a skyrmion-based spin-torque nano-oscillator (STNO) that consists of dual free layers with Dzyaloshinskii-Moriya interaction and interlayer exchange coupling. Micromagnetic simulation shows that skyrmions in the dual free layers can precess independently by application of a spin-polarized current at the center of the ferromagnetic nanodisk. Compared to single free-layer devices, the dual free-layer structure is expected to enhance the output power of the STNO and reduce the resonance linewidth. We also propose a skyrmion STNO based on voltage-controlled magnetic anisotropy. The skyrmion precession rate is controlled by modulating the perpendicular magnetic anisotropy of the skyrmion precession track. It is possible to increase the frequency of the generated signal by adjusting the precession rate of the skyrmions.