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arXiv 2106.02461cond-mat.mes-hallphysics.optics
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在旋磁光子晶体中观测外尔点对的湮灭

Observation of Weyl point pair annihilation in a gyromagnetic photonic crystal

Gui-Geng Liu, Zhen Gao, Peiheng Zhou, Qiang Wang, Yuan-Hang Hu, Maoren Wang, Chengqi Liu, Xiao Lin, Shengyuan A. Yang, Yihao Yang, Yidong Chong, Baile Zhang

发表信息：
Nature 609(7929), 925-930 (2022)
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AI总结：

本文在微波旋磁三维光子晶体中通过连续调节磁场，实验观测到单对外尔点的湮灭及三维陈绝缘体的形成，并揭示了费米弧态向拓扑绝缘体表面态的演化过程。

摘要：

外尔半金属是无带隙的三维（3D）相，其能带结构包含外尔点（WP）简并。外尔点携带拓扑荷，只能通过相互湮灭被消除，这一过程会产生各种拓扑上不同的三维绝缘体。时间反演（T）对称的外尔相至少包含四个外尔点，已在真实材料、光子超材料和其他系统中得到广泛研究。只含有一对外尔点的外尔相——外尔点的最简单构型——更为难以实现，因为它们需要破坏时间反演对称性。在此，我们实现了一种微波尺度的旋磁三维光子晶体，并利用场映射实验追踪了一对理想外尔点，它们在动量空间中的位置强烈依赖于偏置磁场。通过连续改变磁场强度，我们观测到外尔点的湮灭，以及三维陈绝缘体的形成，这是三维拓扑绝缘体（TI）家族中此前未曾实现的一员。表面测量以前所未有的细节展示了连接外尔点的费米弧态如何演化为拓扑绝缘体表面态。

英文摘要：

Weyl semimetals are gapless three-dimensional (3D) phases whose bandstructures contain Weyl point (WP) degeneracies. WPs carry topological charge and can only be eliminated by mutual annihilation, a process that generates the various topologically distinct 3D insulators. Time reversal (T) symmetric Weyl phases, containing a minimum of four WPs, have been extensively studied in real materials, photonic metamaterials, and other systems. Weyl phases with a single WP pair - the simplest configuration of WPs - are more elusive as they require T-breaking. Here, we implement a microwave-scale gyromagnetic 3D photonic crystal, and use field-mapping experiments to track a single pair of ideal WPs whose momentum space locations depend strongly on the biasing magnetic field. By continuously varying the field strength, we observe the annihilation of the WPs, and the formation of a 3D Chern insulator, a previously unrealised member of the family of 3D topological insulators (TIs). Surface measurements show, in unprecedented detail, how the Fermi arc states connecting the WPs evolve into TI surface states.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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