Ideal Type-II Weyl Phase and Topological Transition in Phononic Crystals

作者：Huang, Xueqin; Deng, Weiyin^*; Li, Feng; Lu, Jiuyang^*; Liu, Zhengyou^*

来源：Physical Review Letters, 2020, 124(20): 206802.

DOI：10.1103/PhysRevLett.124.206802

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• SEMIMETAL
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Ideal Weyl points, which are related by symmetry and thus reside at the same frequency, could offer further insight into theWeyl physics. The ideal type-IWeyl points have been observed in photonic crystals, but the ideal type-IIWeyl points with tilted conelike band dispersions are still not realized. Here we present the observation of the ideal type-II Weyl points of the minimal number in three-dimensional phononic crystals and, in the meantime, the topological phase transition from the Weyl semimetal to the valley insulators of two distinct types. The Fermi-arc surface states are shown to exist on the surfaces of the Weyl phase, and the Fermi-circle surface states are also observed, but on the interface of the two distinct valley phases. Intriguing wave partition of the Fermi-circle surface states is demonstrated.

• 单位
  武汉大学