Parametric spin wave excitation and cascaded processes during switching in thin films

A theory for calculating the threshold precession angles required to parametrically excite spin waves during large-angle switching of in-plane magnetized films is presented. Analytic expressions for the parametric thresholds are found for finite thickness films when due to three- and four-wave decays. Precession at the threshold angle will produce appreciable spin wave amplitudes only after infinite time. We show that much larger angles are required to experimentally observe nonlinearities within a finite time. This may explain apparent discrepancies reported between ultrafast pulsed reversal and longer time scale high-power ferromagnetic resonance experiments. A comparison of our results to published experimental data for metallic Permalloy films is made. Finally, the film thickness dependence of the threshold is examined and a minimum is found corresponding to when a particular “cascaded” spin wave interaction is resonant

Parametric Amplification of Propagating Spin Waves in Ferrite Films

Amplification of a weak signal spin wave by a strong pump spin wave propagating in yttrium iron garnet film was observed for the first time. A theoretical explanation of this effect is given on the basis of the four-wave parametric processes

Spin waves quantization in patterned exchange-coupled double layers

International audienc

Spin-wave tunnelling through a mechanical gap

We report on the experimental and theoretical investigation of spin-wave tunnelling through a mechanical gap in a ferromagnetic film. Samples with different gap widths were fabricated and the transmission of spin-wave pulses through the gaps was studied. Transmission through the gaps is possible due to the long-range character of the dipole-dipole interaction underlying dynamics of long-wavelength spin waves. By comparing our experimental results with the developed theoretical model, we demonstrate, that the local inhomogeneity of the static magnetisation and the internal field has a significant impact on the transmission

Dipole-exchange propagating spin-wave modes in metallic ferromagnetic stripes

Results from Brillouin light scattering experiments on guided spin waves propagating along metallic magnetic stripes are presented and analyzed. The spin waves propagate along the stripe axis and form mode families due to geometrical confinement in the stripe geometry. In consequence, the allowed wave vectors are quantized in the transverse directions by stripe width and height. We show that each standing spin-wave resonance across the stripe width is associated with a particular guided mode. In the case of stripes magnetized along their length, the group velocity of the guided modes is negative and all modes have a volume character. When the stripes are magnetized along their width, the modes are characterized by a positive group velocity, and the spectrum consists of a series of volume and localized modes

Mode beating of spin wave beams in ferrimagnetic Lu2.04Bi0.96Fe5O12 films

Absract: We report on measurements of the two-dimensional intensity distribtion of linear and non-linear spin wave excitations in a LuBiFeO film. The spin wave intensity was detected with a high-resolution Brillouinlight scatteringspectroscopy setup. The observed snake-like structure of the spin wave intensity distribution is understood as a mode beating between modes with different lateral spin wave intensity distributions. The theoretical treatment of the linear regime is performed analytically, whereas the propagation of non-linear spin waves is simulated by a numerical solution of a non-linear Schrödinger equation with suitable boundary conditions

Resonant frequencies of a binary magnetic nanowire

10.1103/PhysRevB.87.064424Physical Review B - Condensed Matter and Materials Physics876-PRBM

Collective spin waves in a bicomponent two-dimensional magnonic crystal

10.1063/1.4704659Applied Physics Letters10016-APPL