Scalable synchronization of spin-Hall oscillators in out-of-plane field

TL;DR

This paper demonstrates a scalable method for synchronizing spin-Hall oscillators using micromagnetic simulations, highlighting the role of magnetodipolar coupling and robustness against geometrical variations, with potential applications in magnonics.

Contribution

It introduces a simple, scalable design for synchronized spin-Hall oscillator arrays leveraging magnetodipolar coupling, validated through micromagnetic simulations.

Findings

Synchronization occurs across the entire current range inducing self-oscillations.

Robust synchronization despite geometrical differences in contact placement.

Enlarged radiation pattern beneficial for spin-wave generation.

Abstract

A strategy for a scalable synchronization of an array of spin-Hall oscillators (SHOs) is illustrated. In detail, we present micromagnetic simulations of two and five SHOs realized by means of couples of triangular golden contacts on the top of a Pt/CoFeB/Ta trilayer. Results highlight that the synchronization occurs for the whole current region that gives rise to the excitation of self-oscillations. This is linked to the role of the magnetodipolar coupling, which is the phenomenon driving the synchronization when the distance between oscillators is not too large. Synchronization turns out to be also robust against geometrical differences of the contacts, simulated by considering variable distances between the tips ranging from 100nm to 200nm. Besides, it entails an enlargement of the radiation pattern that can be useful for the generation of spin-waves in magnonics applications. Simulations performed to study the effect of the interfacial Dzyaloshinskii-Moriya interaction show nonreciprocity in spatial propagation of the synchronized spin-wave. The simplicity of the geometry and the robustness of the achieved synchronization make this design of array of SHOs scalable for a larger number of synchronized oscillators.