1. Hermitian and non-Hermitian Weyl physics in synthetic three-dimensional piezoelectric phononic beams
- Author
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Liangshu He, Yan Li, Bahram Djafari-Rouhani, Yabin Jin, Tongji University, School of Aerospace Engineering and Applied Mechanics, Northwest University (Xi'an), Physique - IEMN (PHYSIQUE - IEMN), Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-JUNIA (JUNIA), Université catholique de Lille (UCL)-Université catholique de Lille (UCL)-Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-JUNIA (JUNIA), Université catholique de Lille (UCL)-Université catholique de Lille (UCL), ACKNOWLEDGMENTSThis paper is supported by the National Natural Science Foundation of China (Grant No. 12272267), theYoung Elite Scientists Sponsorship Program by CAST(Grant No. 2021QNRC001), and the Shanghai Science andTechnology Committee (Grants No. 22JC1404100 and No.21JC1405600), the program for the professor of specialappointment (Eastern Scholar) at Shanghai Institutions of Higher Learning, the Fundamental Research Funds for the Central Universities., Physique - IEMN [PHYSIQUE - IEMN], and Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 [IEMN]
- Subjects
General Physics and Astronomy ,[PHYS.COND]Physics [physics]/Condensed Matter [cond-mat] ,[SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics - Abstract
International audience; Recently, the evolution of the Weyl point (WP) caused by the introduction of nonhermiticity into Weyl semimetals has aroused great research interest. We consider elastic flexural wave propagation in a phononic beam containing piezoelectric materials and introduce nonhermiticity through active regulation of external circuits. Considering a synthetic parameter space constituted by the one-dimensional Bloch wave vector and two geometrical parameters, we demonstrate that a double WP (DWP) arises at the band crossing. Then we study its evolution from the hermitic to nonhermitic situation under the effect of the active piezoelectric materials. We find that the DWP in the hermitic case evolves into a Weyl degenerate line and a Weyl hollow ring as concerns the real and imaginary parts of the Weyl frequencies, respectively. The formation mechanisms of the DWPs, lines, and rings are explained through the Hamiltonian of the system. Further, we observe the changes of the DWP and degenerate line in the transmission spectra of finite structures. Finally, we discuss the synthetic Fermi arc interface states through the analysis of the reflected phase vortices. In this paper, we provide insights into the high-dimensional Hermitian and non-Hermitian physics in elastic wave systems using synthetic dimensions.
- Published
- 2023