RESUMEN
The resonance property of a magnetic vortex contained within a micron-sized square Py dot was detected using an amplitude-modulated magnetic field excitation technique. We found a significant modulation of the resonant spectra as the external magnetic field changes. The Lorentzian-like spectrum changes from a peak to a dip via a transition of anti-Lorentzian-like spectra. By conducting the micromagnetic simulations, we confirmed that the transition behavior results from the unusual resistance change depending on the vortex core center position. Additionally, the power dependence of the anti-Lorentzian-like spectra revealed a fairly persistent coexistence of peak and dip. Thus, the tunable spectra suggest one way to develop an integratable radiofrequency microcircuits.
RESUMEN
Understanding and manipulating the dynamic properties of the magnetic vortices stabilized in patterned ferromagnetic structures are of great interest owing to the superior resonant features with the high thermal stability and their flexible tunability. So far, numerous methods for investigating the dynamic properties of the magnetic vortex have been proposed and demonstrated. However, those techniques have some regulations such as spatial resolution, experimental facility and sensitivity. Here, we develop a simple and sensitive method for investigating the vortex-core dynamics by using the electrically separated excitation and detection circuits. We demonstrate that the resonant oscillation of the magnetic vortex induced by the amplitude- modulated alternating-sign magnetic field is efficiently picked up by the lock-in detection with the modulated frequency. By extending this method, we also investigate the size dependence and the influence of the magneto-static interaction in the resonant property of the magnetic vortex.
RESUMEN
A magnetic vortex structure stabilized in a micron or nano-sized ferromagnetic disk has a strong potential as a unit cell for spin-based nano-electronic devices because of negligible magnetostatic interaction and superior thermal stability. Moreover, various intriguing fundamental physics such as bloch point reversal and symmetry breaking can be induced in the dynamical behaviors in the magnetic vortex. The static and dynamic properties of the magnetic vortex can be tuned by the disk dimension and/or the separation distance between the disks. However, to realize these modifications, the preparations of other devices with different sample geometries are required. Here, we experimentally demonstrate that, in a regular-triangle Permalloy dot, the dynamic properties of a magnetic vortex are greatly modified by the application of the in-plane magnetic field. The obtained wide range tunability based on the asymmetric position dependence of the core potential provides attractive performances in the microwave spintronic devices.
