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Higher order vortex gyrotropic modes in circular ferromagnetic nanodots
Junjia Ding1, Gleb N Kakazei1, Xinming Liu1
1Information Storage Materials Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, Singapore-117576, Singapore.
Scientific Reports
|April 26, 2014
Summary
We investigated magnetic vortex dynamics in thick Ni80Fe20 dots using ferromagnetic resonance. We discovered thickness-dependent flexure oscillations of the vortex core, offering potential for spin transfer torque oscillators.
Area of Science:
- Condensed Matter Physics
- Materials Science
Background:
- Magnetic vortices are the ground state in confined soft magnetic elements.
- Understanding their dynamics is crucial for spintronic applications.
Purpose of the Study:
- To probe magnetodynamics of thick (50-100 nm) circular Ni80Fe20 dots.
- To investigate thickness-dependent vortex core gyrotropic dynamics.
Main Methods:
- Broadband ferromagnetic resonance (FMR) spectroscopy.
- Analytical theory and micromagnetic simulations.
Main Results:
- Detected spin excitation modes in the gigahertz frequency range.
- Identified flexure oscillations of the vortex core string with n=0,1,2 nodes along the dot thickness.
- Observed significant dependence of the n=1 mode intensity on dot thickness and diameter.
Conclusions:
- Exchange-dominated modes are flexure oscillations of the vortex core.
- The n=1 mode can be more intense than the uniform n=0 mode.
- These findings show promise for developing spin transfer torque oscillators.
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