Manipulation of Time- and Frequency-Domain Dynamics by Magnon-Magnon Coupling in Synthetic Antiferromagnets

Abstract

Magnons (the quanta of spin waves) could be used to encode information in beyond Moore computing applications. In this study, the magnon coupling between acoustic mode and optic mode in synthetic antiferromagnets (SAFs) is investigated by micromagnetic simulations. For a symmetrical SAF system, the time-evolution magnetizations of the two ferromagnetic layers oscillate in-phase at the acoustic mode and out-of-phase at the optic mode, showing an obvious crossing point in their antiferromagnetic resonance spectra. However, the symmetry breaking in an asymmetrical SAF system by the thickness difference, can induce an anti-crossing gap between the two frequency branches of resonance modes and thereby a strong magnon-magnon coupling appears between the resonance modes. The magnon coupling induced a hybridized resonance mode and its phase difference varies with the coupling strength. The maximum coupling occurs at the bias magnetic field at which the two ferromagnetic layers oscillate with a 90° phase difference. Besides, we show how the resonance modes in SAFs change from the in-phase state to the out-of-phase state by slightly tuning the magnon-magnon coupling strength. Our work provides a clear physical picture for the understanding of magnon-magnon coupling in a SAF system and may provide an opportunity to handle the magnon interaction in synthetic antiferromagnetic spintronics.

Bias field orientation driven reconfigurable magnonics and magnon−magnon coupling in triangular shaped Ni80Fe20 nanodot arrays

“…Nevertheless, the most remarkable aspect is that at j = 15°, the mode quantization number (4,1) and spatial distribution of phase match exactly for F1 and F2 modes with a constant phase difference (of ~90°). Such a phase difference of ~90°between two interacting modes due to strong magnon−magnon coupling has already been reported in synthetic antiferromagnetic systems [61]. Therefore, here too we anticipate the presence of magnon−magnon coupling between modes F1 and F2, presumably via the dynamic dipolar interaction as observed in other nanomagnetic systems before [19,31].…”

Hybrid magnonics in hybrid perovskite antiferromagnets

“…In Fig. 2c, d , a dip in the acoustic mode frequency, as well as a discontinuity in the optical mode frequency is observed at 30 mT, which is an indication of the spin-flop transition 39 , consistent with the behavior of the MH loops for the magnetic field applied along the a -axis and parallel to the DMI vector. Additionally, the optical mode frequency for all four configurations reaches zero at 150 mT, consistent with the saturation field obtained from magnetometry and the assumption to treat Cu-EA as an easy-plane antiferromagnet.…”

Phase coupling of acoustic and optical modes in antiferromagnetic materials CrCl3

“…Typically, Chen et al observed the anti-crossing gap between the FM resonance of nanowires and the in-plane standing spin wave of YIG films, and proposed that both interlayer exchange coupling and dynamic coupling are helpful to observe the anti-crossing of the two modes [23]. In this series of expanding research fields, some synthetic AFMs have also been designed as platforms for studying magnon-magnon coupling (mainly embodied in acoustic mode and optical mode) [27][28][29][30][31][32][33]. Overall, magnon-magnon coupling has been widely reported in single magnet, magnetic bilayers and synthetic AFM.…”