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Observation of exceptional points in magnonic parity-time symmetry devices.

ABSTRACT: Non-Hermitian Hamiltonians may still have real eigenvalues, provided that a combined parity-time (??) symmetry exists. The prospect of ?? symmetry has been explored in several physical systems such as photonics, acoustics, and electronics. The eigenvalues in these systems undergo a transition from real to complex at exceptional points (EPs), where the ?? symmetry is broken. Here, we demonstrate the existence of EP in magnonic devices composed of two coupled magnets with different magnon losses. The eigenfrequencies and damping rates change from crossing to anti-crossing at the EP when the coupling strength increases. The magnonic dispersion includes a strong "acoustic-like" mode and a weak "optic-like" mode. Moreover, upon microwave radiation, the ?? magnonic devices act as magnon resonant cavity with unique response compared to conventional magnonic systems.

SUBMITTER: Liu H

PROVIDER: S-EPMC6874485 | biostudies-literature | 2019 Nov

REPOSITORIES: biostudies-literature

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Observation of exceptional points in magnonic parity-time symmetry devices.

Liu Haoliang H Sun Dali D Zhang Chuang C Groesbeck Matthew M Mclaughlin Ryan R Vardeny Z Valy ZV

Science advances 20191122 11

Non-Hermitian Hamiltonians may still have real eigenvalues, provided that a combined parity-time (ƤƮ) symmetry exists. The prospect of ƤƮ symmetry has been explored in several physical systems such as photonics, acoustics, and electronics. The eigenvalues in these systems undergo a transition from real to complex at exceptional points (EPs), where the ƤƮ symmetry is broken. Here, we demonstrate the existence of EP in magnonic devices composed of two coupled magnets with different magnon losses. ...[more]

PMID: 31803837

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