Pseudomagnetic fields in bilayer phononic crystals

¹ School of Physics and Optoelectronics, South China University of Technology Guangzhou, Guangdong 510640, China
² Key Laboratory of Artificial Micro- and Nanostructures of Ministry of Education and School of Physics and Technology, Wuhan University - Wuhan 430072, China
³ Institute for Advanced Studies, Wuhan University - Wuhan 430072, China

Received: 11 March 2024
Accepted: 3 May 2024

Abstract

Pseudomagnetic field (PMF), as an artificial gauge field, has attracted widespread attention in the exploration of magnetic-like effects in artificial structural materials. It offers a novel mechanism for manipulating wave fields in classical wave systems where there is no or weak response to actual magnetic fields. In this work, we construct acoustic PMFs in bilayer phononic crystals by imposing uniaxial linear gradient strain on the scatterers of both layers. Under the PMFs, the linear nodal rings, occurring at around the K and points of the bilayer phononic crystals, split into acoustics Landau levels (LLs). Specifically, the n = 0 plateau of the LLs splits into two discrete ones due to the interlayer coupling. Furthermore, we construct two heterostructures by splicing two phononic crystals with opposite PMFs and observe unique in-plane snake-like propagations of the edge state as well as oscillations between the upper and lower layers. Bilayer structure provides additional degree of freedom to generate PMFs in various types of semimetals and enriches the manipulation of acoustic wave propagations. In addition, it can be extended to other classical wave systems, such as electromagnetic wave and mechanical systems.