New Method Controls Synchronisation in Spin Hall Nano-Oscillators Using Spin Waves

A recent breakthrough in spintronic technology has demonstrated how phase-tunable synchronisation can be achieved in spin Hall nano-oscillators (SHNOs). These nanoscale devices generate high-frequency microwave signals by converting direct current into spin wave auto-oscillations. The ability to control synchronisation between SHNOs is expected to improve applications in telecommunications, neuromorphic computing, and optimisation hardware. The study, conducted by researchers at the University of Gothenburg in Sweden and Tohoku University in Japan, highlights the role of propagating spin waves in enabling phase information transfer between SHNOs.

Phase Control Through Spin Waves

According to the study published in Nature Physics, experimental evidence has confirmed that spin-wave-mediated mutual synchronisation between SHNOs is possible. Unlike earlier systems that relied on nearest-neighbor interactions, the use of propagating spin waves has allowed long-range, one-to-one coupling. Akash Kumar, the first author of the study, explained to Phys.org that this research was motivated by previous findings on propagating spin waves in SHNOs. The team utilised optimised thin-film materials, specifically W/CoFeB/MgO, to facilitate this coupling.

Experimental Validation and Potential Applications

The study’s findings were supported by electrical measurements and advanced microscopy techniques. High-frequency spectrum analysers were used to detect phase-tuned synchronisation, while phase-resolved Brillouin light scattering (μ-BLS) microscopy provided direct visualisation of oscillator phase alignment. Victor H. González, a graduate student and co-author of the study, confirmed the results through micromagnetic simulations. Kumar stated that the ability to transfer phase information between SHNOs has significant implications for Ising machines, which are used for combinatorial optimisation tasks. Future research will focus on scaling the system and incorporating voltage gating to enhance control and energy efficiency in spintronic devices.