Magnetic damping: domain wall dynamics versus local ferromagnetic resonance

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Magnetic relaxation significantly influences magnetization dynamics.
• Varying experimental methods yield different damping parameter values for the same magnetic material.
• Discrepancies in reported damping parameters hinder accurate modeling of magnetic nanostructures.

Purpose of the Study:

• To experimentally resolve discrepancies in magnetic damping parameter measurements.
• To investigate the influence of nonlocal texture on magnetic damping.
• To improve the accuracy of micromagnetic simulations for magnetization dynamics.

Main Methods:

• Experimental measurement of the damping parameter using local ferromagnetic resonance (α=0.0072).
• Experimental measurement of the damping parameter using field-driven domain wall dynamics (α=0.023).
• Micromagnetic simulations incorporating nonlocal texture-induced damping.

Main Results:

• Different experimental techniques yielded distinct damping parameter values (α=0.0072 vs. α=0.023).
• Standard micromagnetic simulations considering only roughness could not explain the observed damping differences.
• Including nonlocal texture-induced damping in simulations achieved excellent agreement with experimental observations.

Conclusions:

• Nonlocal texture-induced damping is crucial for accurately modeling magnetization dynamics in magnetic nanotracks.
• The Gilbert damping parameter is insufficient on its own to capture the full picture of magnetic relaxation.
• Accurate simulation of magnetic nanostructures requires incorporating advanced damping mechanisms beyond simple roughness.