Resonant Spin Transmission Mediated by Magnons in a Magnetic Insulator Multilayer Structure

Abstract

While being electrically insulating, magnetic insulators can behave as good spin conductors by carrying spin current with excited spin waves. So far, magnetic insulators are utilized in multilayer heterostructures for optimizing spin transport or to form magnon spin valves for reaching controls over the spin flow. In these studies, it remains an intensively visited topic as to what the corresponding roles of coherent and incoherent magnons are in the spin transmission. Meanwhile, understanding the underlying mechanism associated with spin transmission in insulators can help to identify new mechanisms that can further improve the spin transport efficiency. Here, by studying spin transport in a magnetic‐metal/magnetic‐insulator/platinum multilayer, it is demonstrated that coherent magnons can transfer spins efficiently above the magnon bandgap of magnetic insulators. Particularly the standing spin‐wave mode can greatly enhance the spin flow by inducing a resonant magnon transmission. Furthermore, within the magnon bandgap, a shutdown of spin transmission due to the blocking of coherent magnons is observed. The demonstrated magnon transmission enhancement and filtering effect provides an efficient method for modulating spin current in magnonic devices.

Nonreciprocal Transmission of Incoherent Magnons with Asymmetric Diffusion Length

“…As d varies, the magnetic shape anisotropy of NiFe also changes. However, in our studied samples, the antiferromagnetic exchange interaction at NiFe/YIG interface − plays an important role in maintaining the misalignment angle, leading to the consistent scaling behavior observed here. After extracting L M for different field angles for the two propagation directions, we summarize L M (± k || ) in Figure e (solid dots), which show a clear difference between ± k || directions, confirming the nonreciprocal magnon diffusion.…”

“…On the other hand, the nonreciprocity ratio of the NiFe/YIG device is more than two times larger than that of the MgO and Cu control samples. This is because the antiferromagnetic exchange interaction between NiFe and YIG increases the misalignment angle of the equilibrium magnetic moments of the two layers, − , which is beneficial for achieving high nonreciprocity in our studied system, as discussed earlier. Besides the classical exchange interaction, it is known that the interfacial DMI can lead to asymmetries in the dispersion relation to cause nonreciprocal spin wave transmission. − To understand the possible role played by DMI in our system, we replace the center NiFe strip with nonmagnetic Pt.…”

Reconfigurable Ferromagnetic Resonances by Engineering Inhomogeneous Magnetic Textures in Artificial Magnonic Crystals

“…[ 21,31 ] Consequently, these MCs with ordered magnetic textures exhibit abundant collective excitation modes that determine the ferromagnetic resonances (FMRs) of the magnetic system. [ 27,28,32,33 ] Compared to dot lattices with magnetic vortices, [ 34,35 ] antidot lattices with non‐magnetic holes periodically present the resonant frequency of gigahertz, [ 36 ] which is significant for the high‐frequency and wide‐band applications, such as electromagnetic compatibility in 5th‐generation wireless communications. [ 37 ] The resonant spectra of antidot lattices can also be manipulated by varying the lattice constant [ 38 ] and symmetry [ 39 ] of antidot lattices, as well as the direction of external magnetic fields.…”

Unconventional Spin Pumping and Magnetic Damping in an Insulating Compensated Ferrimagnet

“…[23][24][25] In addition, spin angular momentum can be transferred by the magnon spin current without involving charge current between the GdIG films and the adjacent materials, although GdIG is electrically insulating. [26] Such an insulating compensated ferrimagnet provides a promising platform for exploring ferrimagnetic spin dynamics and low-dissipation magnonic devices. Here, we report an unconventional SP and the associated magnetic damping in GdIG-based heterostructures.…”