A numerical method has been recently proposed to calculate spin modes in ferromagnetic nanoparticles. The magnetic particle is divided into cells; the magnetization, uniform in each cell, precesses around its equilibrium direction under the influence of the external field and the dipolar and exchange forces. The dynamic coupled equations are solved and the magnonic normal modes of the particle are calculated, with the Brillouin light scattering (BLS) cross section. We present an application to permalloy thin cylindrical dots of thickness 15 nm and radius 100 nm. Sample consists of a square array of dots prepared by means of electron-beam lithography; the spin spectra have been measured by BLS. Good agreement between experimental and calculated mode frequencies is obtaned, as shown in the figure, as function of the in-plane applied field spanning the vortex and uniform magnetization states.
Magnetic normal modes of nanoparticles: application to ferromagentic cylindrical dots
GIOVANNINI, Loris;MONTONCELLO, Federico;NIZZOLI, Fabrizio;
2004
Abstract
A numerical method has been recently proposed to calculate spin modes in ferromagnetic nanoparticles. The magnetic particle is divided into cells; the magnetization, uniform in each cell, precesses around its equilibrium direction under the influence of the external field and the dipolar and exchange forces. The dynamic coupled equations are solved and the magnonic normal modes of the particle are calculated, with the Brillouin light scattering (BLS) cross section. We present an application to permalloy thin cylindrical dots of thickness 15 nm and radius 100 nm. Sample consists of a square array of dots prepared by means of electron-beam lithography; the spin spectra have been measured by BLS. Good agreement between experimental and calculated mode frequencies is obtaned, as shown in the figure, as function of the in-plane applied field spanning the vortex and uniform magnetization states.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
