Controllable frequency tunability in constriction-based spin Hall nano-oscillators for neuromorphic computing
T. M. Arunima, Himanshu Fulara · Journal of Physics D Applied Physics · 2025
Abstract The capability to precisely tune auto-oscillation frequency in spin Hall nano-oscillators (SHNOs) holds great promise across diverse applications, from data communication to neuromorphic computing. This study systematically investigates the controllable frequency tunability of nano-constriction-based SHNOs across distinct operational regimes. Through the independent tuning of critical magnetodynamical parameters-effective magnetization ( μ 0 M eff ) and magnetic damping (α)-we unveil varying impacts on frequency tunability with changes in out-of-plane (OOP) field strengths and constriction widths. At large OOP fields, μ 0 M eff predominantly governs frequency tunability, yielding a current tunability of 1 GHz/mA-four times greater than observed at the lowest μ 0 M eff . At low OOP fields, although we observe a remarkably high frequency-tunability of 4 GHz mA−1, μ 0 M eff alters the onset of transition from a linear-like mode to a spin-wave bullet mode. In contrast, α primarily affects the threshold current with less impact on frequency tunability. Moreover, we demonstrate that M eff-driven frequency tuning enables control over the mutual synchronization of SHNOs, mimicking synaptic-like interactions between artificial neurons. Our findings greatly extend the versatility of SHNOs for oscillator-based neuromorphic computing and provide key insights into the intricate auto-oscillation dynamics under varying OOP fields.