Coherence and modality of driven interlayer-coupled magnetic vortices.

Area of Science:

• Spintronics
• Condensed Matter Physics
• Nanoscience

Background:

• Mode-coupled magnetic vortices are key components in spintronic technologies, particularly spin-torque nano-oscillators.
• Understanding their high-frequency dynamics is essential for device optimization.
• Previous studies focused on spectroscopic analysis, lacking direct visualization of coupled vortex behavior.

Purpose of the Study:

• To directly image and analyze the dynamics of driven interlayer coaxial magnetic vortices.
• To investigate the influence of dipolar and indirect exchange coupling on vortex motion.
• To provide fundamental insights into the collective behavior of vortex-based microwave generators.

Main Methods:

• Utilized in situ high-frequency excitation combined with Lorentz microscopy.
• Achieved sub-5 nm spatial resolution for direct observation of vortex motion.
• Studied vortices in both dipolar- and indirect exchange-coupled regimes.

Main Results:

• Directly observed steady-state orbital amplitudes of driven interlayer coaxial vortices in real space.
• Characterized unique frequency responses, including mode splitting and locking, in coupled vortex motion.
• Quantified variations in coherent motion and resultant orbital amplitudes.

Conclusions:

• This work presents the first direct imaging of driven coupled magnetic vortices.
• The findings offer critical insights into the steady-state amplitudes, tunability, and collective motion of these systems.
• The results are vital for advancing the design and understanding of collective vortex-based microwave generators.