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arXiv 2302.03479cond-mat.mes-hallcond-mat.mtrl-sci
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量子自旋霍尔绝缘体中的光学体边界二分法

Optical bulk-boundary dichotomy in a quantum spin Hall insulator

Junfeng Han, Pengcheng Mao, Hailong Chen, Jia-Xin Yin, Maoyuan Wang, Dongyun Chen, Yongkai Li, Jingchuan Zheng, Xu Zhang, Dashuai Ma, Qiong Ma, Zhi-Ming Yu, Jin… 展开作者

Junfeng Han, Pengcheng Mao, Hailong Chen, Jia-Xin Yin, Maoyuan Wang, Dongyun Chen, Yongkai Li, Jingchuan Zheng, Xu Zhang, Dashuai Ma, Qiong Ma, Zhi-Ming Yu, Jinjian Zhou, Cheng-Cheng Liu, Yeliang Wang, Shuang Jia, Yuxiang Weng, M. Zahid Hasan, Wende Xiao, Yugui Yao

摘要:

体-边界对应是拓扑量子材料中的一个关键概念。例如,量子自旋霍尔绝缘体的特征在于具有由底层Z2拓扑保护的无间隙螺旋边界状态的体绝缘间隙。然而,在光学实验中很少探索体边界二分法和区分,这可以提供关于传输和电子光谱技术之外的拓扑载流子的唯一信息。在这里,我们利用中红外吸收显微光谱和泵浦-探测显微光谱来阐明最近发现的室温量子自旋霍尔绝缘体Bi 4 Br 4的体边界光学响应。得益于红外光子的低能量和高的空间分辨率,我们明确地解决了从边界态的强吸收,而体吸收被其绝缘间隙抑制。此外,边界吸收表现出很强的极化各向异性,与拓扑边界态的一维性质相一致。我们的红外泵浦-探测显微镜进一步测量了边界态的载流子寿命,达到了一纳秒的尺度。纳秒寿命比大多数拓扑材料的寿命长一到两个数量级,并且可以归因于螺旋边界态的线性色散性质。我们的研究结果表明,在拓扑材料的光学体边界二分法,并提供了一个证明的主要方法,研究拓扑光电子学。

英文摘要:

The bulk-boundary correspondence is a key concept in topological quantum materials. For instance, a quantum spin Hall insulator features a bulk insulating gap with gapless helical boundary states protected by the underlying Z2 topology. However, the bulk-boundary dichotomy and distinction are rarely explored in optical experiments, which can provide unique information about topological charge carriers beyond transport and electronic spectroscopy techniques. Here, we utilize mid-infrared absorption micro-spectroscopy and pump-probe micro-spectroscopy to elucidate the bulk-boundary optical responses of Bi4Br4, a recently discovered room-temperature quantum spin Hall insulator. Benefiting from the low energy of infrared photons and the high spatial resolution, we unambiguously resolve a strong absorption from the boundary states while the bulk absorption is suppressed by its insulating gap. Moreover, the boundary absorption exhibits a strong polarization anisotropy, consistent with the one-dimensional nature of the topological boundary states. Our infrared pump-probe microscopy further measures a substantially increased carrier lifetime for the boundary states, which reaches one nanosecond scale. The nanosecond lifetime is about one to two orders longer than that of most topological materials and can be attributed to the linear dispersion nature of the helical boundary states. Our findings demonstrate the optical bulk-boundary dichotomy in a topological material and provide a proof-of-principal methodology for studying topological optoelectronics.

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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