Power and Phase Profiles in Nano-constriction Based Synchronized Spin Hall Nano-oscillators near Threshold Current

Spin Hall nano-oscillators (SHNOs) demonstrate self-sustained magnetization auto-oscillations, that have recently received much attention due to their potential for cutting-edge applications. In this work, the power and phase profiles, i.e., the complex quantized propagation dynamics of nano-constriction-based spin hall nano-oscillators (SHNOs) near the threshold current have been investigated. The SHNO generates a 12 GHz microwave frequency upon application of 2 mA direct current in presence of a 0.6 T external bias magnetic field. Power profile reveals that spin wave (SW) modes are quantized along x-axis. The phase profile reveals a complex nature of the SW modes at the dominant frequency (mostly localised at the nano-constriction region and additionally propagates from centre to the edges). Whereas SW mode of other frequencies mostly propagate towards the edge from the central nano-constriction region having a complex spiral nature. The SHNO devices, which are operational at high-frequencies, can be useful in energy-efficient tuneable microwave oscillators and neuromorphic computing.