Direct current-tunable MHz to multi-GHz skyrmion generation and control

Area of Science:

• Spintronics
• Condensed Matter Physics
• Materials Science

Background:

• Skyrmions are nanoscale, topologically-protected chiral spin structures offering high density, low power, and nonvolatile memory.
• Controlling skyrmion generation and propagation rates with current is crucial for integrated high-bandwidth devices.

Purpose of the Study:

• To introduce a novel method for initializing and controlling skyrmion generation using spin-polarized direct current.
• To demonstrate tunable skyrmion generation frequencies for potential applications in advanced circuits.

Main Methods:

• A stable magnetic domain profile is initialized using a DC pulse and pinned between a notch and a rectangular constriction.
• Spin-polarized DC charge current is applied to eject periodic skyrmions at desired frequencies.
• Micromagnetic simulations are used to analyze the control of skyrmion generation frequencies.

Main Results:

• Periodic skyrmions were generated at frequencies ranging from 114 MHz to 21 GHz.
• Skyrmion generation frequencies were controlled reversibly over seven octaves by adjusting DC current density.
• A highly tunable, DC-controlled skyrmion signal source was demonstrated.

Conclusions:

• The developed method enables precise control over skyrmion generation frequency using spin-polarized DC current.
• This technique paves the way for ultra-wideband, compact, and integrated skyrmionic circuits.
• The study highlights the potential of domain pinning and current-driven skyrmion motion for future spintronic devices.