Controlling the influence of elastic eigenmodes on nanomagnet dynamics through pattern geometry

Abstract

The effect of the nanoscale array geometry on the interaction between optically generated surface acoustic waves (SAWs) and nanomagnet dynamics is investigated using Time-Resolved Magneto-Optical Kerr Effect Microscopy (TR-MOKE). It is demonstrated that altering the nanomagnet geometry from a periodic to a randomized aperiodic pattern effectively removes the magneto-elastic effect of SAWs on the magnetization dynamics. The efficiency of this method depends on the extent of any residual spatial correlations and is quantified by spatial Fourier analysis of the two structures. Randomization allows observation and extraction of intrinsic magnetic parameters such as spin wave frequencies and damping to be resolvable using alloptical methods, enabling the conclusion that the fabrication process does not affect the damping.

Strongly coupled magnon–phonon dynamics in a single nanomagnet

“…, and was extracted at 4.6 kOe, away from the crossing point, so that the mode is predominantly magnetic in character. This value is consistent with previous measurements we have made on the damping in Ni 9 . The loss rate of the phononic system, κ P , is extracted from the non-magnetic signal.…”

“…(3). The anticrossing is empirical evidence of the coupling between the magnon and phonon systems, and has not been observed in other experiments utilizing acoustic waves as an excitation mechanism 9,14 . In order to determine the coupling regime of the magnon–phonon resonances, we analyze the loss rates of the different systems by employing a least- squares curve-fitting algorithm to the decaying sinusoids in the time-domain signals.…”

“…Significant effects of optically excited SAWs on the magnetization dynamics of patterned nanomagnet arrays have been demonstrated 8 . In these systems, the SAW frequencies arise from the geometric arrangement of the elements 9 , with the SAW energy located in the substrate layer below the nanoelements. Due to the magneto-elastic coupling, the magnetic resonance is pinned at the SAW frequency.…”

Controlling acoustic waves using magneto-elastic Fano resonances

“…7,11,12 The phenomena resulting from interaction between coherent spin and acoustic waves have already been addressed in the research literature: the spin wave excitation of propagating acoustic waves 7,[13][14][15] and vice versa, 8,[16][17][18] acoustic parametric pumping of spin waves, [19][20][21] magnon-phonon coupling in cavities [22][23][24] and mode locking, 25 magnonicphononic crystals, 26,27 Bragg scattering of spin waves from a surface acoustic wave induced grating, [28][29][30] topological properties of magneto-elastic excitations, 15,31 acoustically driven spin pumping and spin Seebeck effect, 32,33 and optical excitation and detection of magneto-acoustic waves. [34][35][36][37][38][39][40] However, studies of the interaction between propagating acoustic waves and spin wave modes of finite-sized magnetic elements, which are the most promising for applications, have been relatively scarce to date. 10 Here, we explore theoretically a class of magneto-acoustic devices in which the signal is carried by acoustic waves while the magnetic field controls its propagation via the magnetoelastic interaction in thin isolated magnetic inclusions as shown in Fig.…”

Spin Wave Electromagnetic Nano‐Antenna Enabled by Tripartite Phonon‐Magnon‐Photon Coupling

“…[ 4 , 5 ] Coupling between magnons and phonons was also studied, aided by extensive simulations. [ 6 , 7 , 8 ] Strong coupling leads to the formation of a hybridized magnon‐phonon quasi‐particle called a magnon polaron. [ 9 , 10 ] Other studies of coupling between spin waves and SAW have also been reported.…”