  Spintronic nano-oscillators can generate tunable microwave signals that find
a wide range of applications in the field of telecommunication to modern
neuromorphic computing systems. Among other spintronic devices, a magnetic
skyrmion is a promising candidate for the next generation of low-power devices
due to its small size and topological stability. In this work, we propose a
multi-channel oscillator design based on the synthetic anti-ferromagnetic (SAF)
skyrmion pair. The mitigation of the skyrmion Hall effect in SAF and the
associated decimation of the Magnus force endows the proposed oscillator with
an ultra-high frequency of 41GHz and a multi-channel frequency output driven by
the same current. The ultrahigh operational frequency represents an $\sim$342
times improvement compared to the monolayer single skyrmion oscillator
featuring a constant uniaxial anisotropy profile. Using micromagnetic
simulations, we demonstrate the effectiveness of our proposed multi-channel
oscillator design by introducing multi-channel nanotracks along with multiple
skyrmions for enhanced frequency operation. The ultrahigh operational frequency
and multi-channel output are attributed to three key factors: The oscillator
design accounting for a finite spin-flip length of the spacer (such as Ru)
material, tangential velocity proportionality on input spin current along with
weak dependence on the radius of rotation of the skyrmion-pair, skyrmion
interlocking in the channel enabled by the multi-channel high Ku rings and
skyrmion-skyrmion repulsion, therefore resulting ultrahigh frequency and
multi-channel outputs.
