# Dynamical mode coupling and coherence in spin Hall nano-oscillator with perpendicular magnetic anisotropy

## TL;DR

This study investigates the dynamical modes and coherence properties of spin Hall nano-oscillators with perpendicular magnetic anisotropy, revealing mode control, thermal effects, and achieving narrow linewidth oscillations without external fields.

## Contribution

It provides experimental insights into mode coupling, thermal effects, and coherence control in spin Hall nano-oscillators with perpendicular magnetic anisotropy, including achieving single-mode oscillations at zero field.

## Key findings

- Propagating and localized modes can be controlled by magnetic field and current.
- Mode hopping is suppressed at cryogenic temperatures due to reduced thermal magnons.
- Coherent single-mode oscillations with 5 MHz linewidth are achieved without external magnetic field.

## Abstract

We experimentally study the dynamical modes excited by spin current in Spin Hall nano-oscillators based on the Pt/[Co/Ni] multilayers with perpendicular magnetic anisotropy. Both propagating spin wave and localized solitonic modes of the oscillation are achieved and controlled by varying the applied magnetic field and current. At room temperature, the generation linewidth broadening associated with mode hopping was observed at currents close to the transition between different modes and in the mode coexistence regimes. The mode hopping was suppressed at cryogenic temperatures, confirming that the coupling between modes is mediated by thermal magnons. We also demonstrate that coherent single-mode oscillations with linewidth of 5 MHz can be achieved without applying external magnetic field. Our results provide insight into the mechanisms controlling the dynamical coherence in nanomagnetic oscillators, and guidance for optimizing their applications in spin wave-based electronics.