Broadband spin dynamics of the magnetic vortex state: Effect of the pulsed field direction

Abstract

The dynamic spin modes observed in magnetic vortex structures are shown to depend strongly on the nature of the initial excitation by a transient pulse field. In submicrometer-sized Permalloy disks, when a uniform perpendicular transient field is used to perturb the magnetization, radial standing-wave modes are excited; whereas if an in-plane transient field is used, angular or azimuthal modes are formed. The existence of the vortex core is responsible for a frequency splitting of the azimuthal modes, as demonstrated through comparison to micromagnetic simulations of a ring geometry

Influence of domain wall pinning on the dynamic behavior of magnetic vortex structures: Time-resolved scanning x-ray transmission microscopy in NiFe thin film structures

“…The lowest frequency mode of a vortex configuration is the gyrotropic mode, which can be excited by using an in-plane magnetic field pulse. 2 Such an excitation results in a displacement of the vortex core and the consecutive gyration back to its equilibrium state. This dynamic behavior has been explained as the movement of the vortex core in its self-induced magnetostatic restoring force.…”

Spin waves in circular soft magnetic dots at the crossover between vortex and single domain state

“…Our experimental results and simulations could be relevant for different vortex systems in the confined stratified conditions. Two sets of square arrays of Py circular dots were fabricated by combination of lithography and lift-off techniques on a standard Si(100) substrate as explained elsewhere [15,20,21]. The first set includes three samples with thickness L=50 nm, diameter D=1000 nm and the dot´s lattice parameters (center-to-center distance, d) of 1200, 1500 and 2500 nm.…”

“…Previous studies were mainly focused on resonant response in the absence of bias magnetic field [6][7][8][9]11,12,14,15] when the static vortex was localized in the dot center. Our letter reports on broadband measurements of the vortex dynamics in circular Permalloy (Py) dots excited by applying in-plane stratifying field with the variable angle between the bias and excitation fields.…”

“…The lowest frequency excitation corresponds to the gyrotropic mode when the vortex moves as a whole around an equilibrium position [7][8][9], meanwhile the higher frequency modes correspond to the spin waves excited mainly outside of the vortex core [10][11][12][13][14][15][16][17][18][19]. The spin wave having radial or azimuthal symmetry with respect to the dot center are described by integers (n, m), which indicate number of nodes in the dynamic magnetization along radial (n) and azimuthal (m) directions.…”

Magnetic Vortices in Ferromagnetic Nanodots

“…There are various experimental techniques for observation of high-frequency azimuth modes [35,36,52]. A series of experiments on measuring the excited spin-wave azimuth modes was carried out and it was established that the eigenfrequencies are much lower than the frequencies obtained by computer simulation [35].…”