Giant Nonreciprocity of Surface Acoustic Waves enabled by the Magnetoelastic Interaction

Nonreciprocity, the defining characteristic of isolators, circulators and a wealth of other applications in radio/microwave communications technologies, is in general difficult to achieve as most physical systems incorporate symmetries that prevent the effect. In particular, acoustic waves are an im...

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Bibliographic Details
Published in:arXiv.org 2020-04
Main Authors: Shah, Piyush J, Bas, Derek A, Lisenkov, Ivan, Matyushov, Alexei, Sun, Nianxiang, Page, Michael R
Format: Article
Language:English
Subjects:
Acoustic insulation
Aluminum oxide
Band theory
Ferromagnetism
Isolators
Lithium niobates
Microwave communications
Multilayers
Substrates
Surface acoustic wave devices
Surface acoustic waves
Weight reduction
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Summary:Nonreciprocity, the defining characteristic of isolators, circulators and a wealth of other applications in radio/microwave communications technologies, is in general difficult to achieve as most physical systems incorporate symmetries that prevent the effect. In particular, acoustic waves are an important medium for information transport, but they are inherently symmetric in time. In this work, we report giant nonreciprocity in the transmission of surface acoustic waves (SAWs) on lithium niobate substrate coated with ferromagnet/insulator/ferromagnet (FeGaB/Al2O3/FeGaB) multilayer structure. We exploit this novel structure with a unique asymmetric band diagram, and expand on magnetoelastic coupling theory to show how the magnetic bands couple with acoustic waves only in a single direction. We measure 48.4 dB (ratio of 1:100,000) isolation which outperforms current state of the art microwave isolator devices in a novel acoustic wave system that facilitates unprecedented size, weight, and power reduction. Additionally, these results offer a promising platform to study nonreciprocal SAW devices.
ISSN:2331-8422