Giant moving vortex mass in thick magnetic nanodots

Area of Science:

• Condensed matter physics
• Spintronics
• Magnetism

Background:

• Magnetic vortices are simple, topologically non-trivial textures and the ground state in submicron magnetic elements.
• Previous studies focused on thin dots (5-50 nm), observing only uniform vortex excitation modes.
• The dynamics in thicker magnetic dots remain less explored.

Purpose of the Study:

• To investigate the fundamental vortex mode in relatively thick (50-100 nm) magnetic dots.
• To understand how increased dimensionality affects vortex excitation spectra.
• To identify the physical mechanisms governing vortex dynamics in thicker elements.

Main Methods:

• Broadband ferromagnetic resonance spectroscopy was employed.
• Experimental data was analyzed to observe and characterize vortex excitation modes.
• Theoretical considerations involving vortex mass and interactions were introduced.

Main Results:

• Qualitatively new excitation spectra were observed in thicker dots compared to thin dots.
• The fundamental mode frequency necessitates the introduction of a significant vortex mass.
• This giant vortex mass arises from vortex distortion due to spin wave interactions.

Conclusions:

• Increased dot thickness leads to complex vortex dynamics and new excitation spectra.
• A giant vortex mass, dependent on geometry and dipolar interactions, is essential for explaining observations in thicker dots.
• The importance of vortex mass increases significantly with dot thickness.