Imaging magnetic excitations in confined magnetic structures

Abstract

In this paper we revisit some particular aspects concerning the dynamic magnetization of thin Ni 80 Fe 20 discs. In particular we address details of the excitation spectrum of Ni 80 Fe 20 discs subjected to in-plane magnetic cw microwave fields. In this case imaging the dynamic magnetization allows us to estimate the internal magnetic field of the ferromagnetic element.

Magnonic Metamaterials

“…Spin-wave quantization due to the finite size effect was discovered in thin films 51,52 and more recently in laterally confined magnetic structures 53,54,55,56,57,58 , with their effect upon the high frequency permeability and the observation of a negative permeability discussed in Refs. 7 and 59, respectively.…”

“…In the case of the effective permeability of magnetic composites and metamaterials, the majority of analytical models employ the so-called macrospin approximation, in which each magnetic inclusion within a non-magnetic matrix is considered as a single giant spin and is therefore characterized by a single magnetic resonance. However, it is well known that the spin wave spectrum of magnetic nanostructures and nano-elements has a complex structure, featuring series of resonances due to spatially non-uniform spin wave modes [54][55][56]61,64,[67][68][69]71,[92][93][94][95][96][97][98][99]115,119 . Each of the resonances is expected to contribute to the susceptibility tensor of the magnetic constituents and correspondingly to the permeability tensor of the whole metamaterial.…”

Vortices in two-dimensional nanorings studied by means of the dynamical matrix method

“…In the last case the observed lowest-frequency mode is usually fundamental mode (0, 0) [37,[54][55][56]. On the other hand, for in-plane pumping a first order azimuthal mode is usually reported as the lowest one [33,35,54,55,57]. …”

“…In the literature different types of modes are reported to be observed. For example, the observed lowest-frequency mode is an azimuthal mode of different order [53][54][55][56], a localized mode [45,[57][58][59], or even the fundamental mode [37]. In Ref.…”

Analytical expression of the magneto-optical Kerr effect and Brillouin light scattering intensity arising from dynamic magnetization

“…TR-MOKE investigations are based on repeated excitations of magnetization dynamics, usually by magnetic field pulses or by intense light pulses [11][12][13]. The resulting excitations are then stroboscopically detected making use of the MOKE.…”