Observation of Coherence and Partial Decoherence of Quantized Spin Waves in Nanoscaled Magnetic Ring Structures

Abstract

Experiments and simulations are reported, which demonstrate the influence of partial decoherence of spin-wave modes on the dynamics in small magnetic structures. Microfocus Brillouin light scattering spectroscopy was performed on 15 nm thick Ni81Fe19 rings with diameters from 1 to 3 microm. For the so-called "onion" magnetization state several effects were identified. First, in the pole regions of the rings spin-wave wells are created due to the inhomogeneous internal field leading to spin-wave confinement. Second, in the regions in between, modes are observed which show a well pronounced quantization in radial direction but a transition from partial to full coherency in azimuthal direction as a function of decreasing ring size. In particular for larger rings a continuous frequency variation with position is observed which is well reproduced by spin-wave calculations and micromagnetic simulations.

Realization of a spin-wave multiplexer

“…To evaluate the functionality of the proposed spin-wave multiplexer, we employed Brillouin light scattering (BLS) microscopy 20,21 . Measuring the BLS intensity for various excitation frequencies inside the arms of the Y-shaped multiplexer enables us to determine whether the spin-wave propagation path can be switched.…”

Magnetic Vortices in Ferromagnetic Nanodots

“…In recent years the dynamic properties of ferromagnetic nanodot arrays have been studied both experimentally and theoretically [11][12][13][14][15][16]. The numerical and analytical calculations were performed with the use of various model functions of magnetization distribution inside the vortex [6,17,18].…”

Comparative study of the ferromagnetic resonance behavior of coupled rectangular and circular Ni80Fe20rings

“…In circular rings, the boundaries of the structure as well as inhomogeneous internal fields become the source of spin wave confinement [36] and determine whether spin wave propagation is allowed or forbidden. In nanowires and nanostrips, the existence of bends and kinks also introduces nonuniform internal fields that can change the character of propagating spin waves or act as a propagation barrier [37].…”