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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.
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Excitation and Amplification of Spin Waves by Spin–Orbit Torque
Abstract The emerging field of nanomagnonics utilizes high‐frequency waves of magnetization—spin waves—for the transmission and processing of information on the nanoscale. The advent of spin‐transfer torque has spurred significant advances in nanomagnonics, by enabling highly efficient local spin wave generation in magnonic nanodevices. Furthermore, the recent emergence of spin‐orbitronics, which utilizes spin–orbit interaction as the source of spin torque, has provided a unique ability to exert spin torque over spatially extended areas of magnonic structures, enabling enhanced spin wave transmission. Here, it is experimentally demonstrated that these advances can be efficiently combined. The same spin–orbit torque mechanism is utilized for the generation of propagating spin waves, and for the long‐range enhancement of their propagation, in a single integrated nanomagnonic device. The demonstrated system exhibits a controllable directional asymmetry of spin wave emission, which is highly beneficial for applications in nonreciprocal magnonic logic and neuromorphic computing.
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- Award ID(s):
- 1804198
- PAR ID:
- 10062526
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials
- Volume:
- 30
- Issue:
- 33
- ISSN:
- 0935-9648
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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