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Bistability of vortex core dynamics in a single perpendicularly magnetized nanodisk
G de Loubens1, A Riegler, B Pigeau
1Service de Physique de l'Etat Condensé (CNRS URA 2464), CEA Saclay, 91191 Gif-sur-Yvette, France. gregoire.deloubens@cea.fr
Physical Review Letters
|June 13, 2009
Summary
We used microwave spectroscopy to detect the magnetic vortex core polarity in nanodisks. The gyrotropic frequency splitting allows for polarity detection and analysis of bistable dynamics.
Area of Science:
- Condensed matter physics
- Materials science
- Nanotechnology
Background:
- Vortex-state magnetic nanodisks exhibit complex dynamics.
- Controlling and detecting magnetic states at the nanoscale is crucial for data storage applications.
Purpose of the Study:
- To investigate the influence of a perpendicular bias magnetic field on the gyrotropic frequency of magnetic vortex cores.
- To develop a spectroscopic method for detecting the polarity of the magnetic vortex core.
- To quantitatively describe the observed bistable dynamics.
Main Methods:
- Microwave spectroscopy was performed on individual vortex-state magnetic nanodisks.
- A magnetic resonance force microscope was utilized for high-resolution measurements.
- Analytic theory and micromagnetic simulations were employed for theoretical analysis.
Main Results:
- A magnetic field-induced splitting of the gyrotropic frequency was observed, directly related to the vortex core's polarity.
- This frequency splitting enabled spectroscopic detection of the core polarity.
- Bistability of the core polarity was observed up to significant negative magnetic fields.
- The frequency difference between the two stable modes is proportional to the applied field and the disk's aspect ratio (thickness to radius).
Conclusions:
- The study demonstrates a novel spectroscopic technique for determining magnetic vortex core polarity.
- The observed bistable dynamics can be quantitatively described by analytic theory and micromagnetic simulations.
- This work provides insights into the fundamental magnetic properties of nanodisks and their potential for spintronic applications.
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