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arXiv · 2606.26810

Giant and Broadband Circular Dichroism from Particle-Hole Symmetry Breaking in Weyl Semimetals

Xiangyu Jiang·Zeping Shi·Yuhan Du·Haonan Chen·Jiayu Wang·Wenbin Wu·Guangyi Wang·Congming Hao·Mingfan Yao·Mingsen Zhou·Xin Chen·Chenyao Xu·Zhongbo Yan·Cheng Zhang·Hai-Zhou Lu·Junhao Chu·Xiang Yuan
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Abstract

Circular dichroism originates from symmetry breaking of material structure, leading to differential absorption of left- and right-circularly polarized light. However, circular dichroism in most materials is inherently weak and spectrally narrow, especially in the mid-to-far infrared. Here, we uncover giant infrared circular dichroism in the magnetic-field-forced Weyl semimetal Mn(Bi,Sb)2Te4, driven by extreme particle-hole symmetry breaking. Helicity-resolved magneto-infrared spectroscopy reveals circular dichroism exceeding 3000 mdeg (~130 mdeg/nm) with above-degree response extending over the 6-13 {\mu}m spectral range. The optical resonances are enhanced by a strong band nesting effect intrinsic to the Landau levels of type-II Weyl dispersion. A symmetry-based kp model reproduces these magneto-infrared responses and demonstrates that magnetization-induced asymmetric spin-orbit coupling generates particle-hole symmetry breaking, suppressing spin-up, parity-even wavefunction components in the valence Landau band and thereby producing pronounced optical helicity selectivity. Our findings establish particle-hole symmetry breaking as an effective route toward helicity-resolved optical control in quantum materials.

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Xiangyu Jiang, Zeping Shi, Yuhan Du, Haonan Chen, Jiayu Wang, Wenbin Wu, Guangyi Wang, Congming Hao, Mingfan Yao, Mingsen Zhou, Xin Chen, Chenyao Xu, Zhongbo Yan, Cheng Zhang, Hai-Zhou Lu, Junhao Chu, Xiang Yuan. 2026-06-25. Giant and Broadband Circular Dichroism from Particle-Hole Symmetry Breaking in Weyl Semimetals. https://doi.org/10.1038/s41563-026-02630-6

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