论文标题

观察声音晶体中单对III型Weyl点

Observation of Single Pair of Type-III Weyl Points in Sonic Crystals

论文作者

Li, Xiao-Ping, Li, Feng, Zhou, Di, Wu, Ying, Yu, Zhi-Ming, Yao, Yugui

论文摘要

在电子系统中,可以根据费米表面的几何形状将Weyl点分为三种类型,每种类型都表现出各种独特而有趣的现象。虽然I型和II型WEYL点在跨系统和无旋转系统中都达到了,但III型Weyl点的实现仍然具有挑战性,并且在人工周期性系统中尚未报道。在这里,我们首次报告了声音晶体中III型Weyl点的实验观察。值得注意的是,一对型III WEYL点被视为频率范围内唯一的频带交叉点,在实验上反驳了对田间的共同信念,即非磁性系统中的Weyl点最小数量为四个。实验结果与理论预测之间的一致性证实了III型Weyl点,非收集Fermi Arc表面状态和手性边缘状态的存在。我们的工作不仅填补了声音晶体中III型Weyl点的空白,而且还刺激了其他系统(例如光子,机械和冷原子系统)中相关的研究。

In electronics systems, the Weyl points can be classified into three types based on the geometry of the Fermi surface, and each type exhibits various unique and intriguing phenomena. While the type-I and type-II Weyl points have been achieved in both spinful and spinless systems, the realization of type-III Weyl points remains challenging, and has not been reported in artificial periodic systems. Here, we for the first time report the experimental observation of the type-III Weyl points in a sonic crystal. Remarkably, a single pair of type-III Weyl points are observed as the only band crossings in a frequency range, experimentally disproving a common belief in the field, namely, the minimal number of Weyl points in nonmagnetic systems is four. The consistency between experimental results and theoretical predictions confirms the existence of type-III Weyl points, noncontractible Fermi arc surface states, and chiral edge states. Our work not only fill the gap of the type-III Weyl point in sonic crystal but also stimulate related researches in other systems, such as photonic, mechanical and cold atom systems.

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