Layer-by-layer disentanglement of Bloch states
Layer-by-layer disentanglement of Bloch states
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DOI：
10.1038/s41567-023-02008-4
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发表时间：
2023-01
期刊：
影响因子：
19.6
通讯作者：
Woojoo Lee;Sebastian Fernandez-Mulligan;Hengxin Tan;Chenhui Yan;Yingdong Guan;S. Lee;Ruobing Mei
中科院分区：
文献类型：
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作者：
Woojoo Lee;Sebastian Fernandez-Mulligan;Hengxin Tan;Chenhui Yan;Yingdong Guan;S. Lee;Ruobing Mei
逐层材料工程产生了有趣的量子现象，例如界面超导和量子反常霍尔效应。然而，逐层探测电子态仍然具有挑战性。理解磁性拓扑绝缘体中拓扑电子态的层起源的困难就证明了这一点。在这里，我们报告了磁拓扑绝缘体 (MnBi2Te4)(Bi2Te3) 上的层编码频域光电子实验，该实验表征了其电子态的起源。红外激光激发发射相干晶格振动，层指数由振动频率编码。然后光电发射光谱跟踪电子动力学，其中层信息在频域中携带。这种层频对应关系显示了拓扑表面态从顶部磁性层到掩埋第二层的波函数重定位，调解了关于 (MnBi2Te4)(Bi2Te3) 及其相关化合物中对称性破缺能隙消失的争议。可以利用层频率对应关系在广泛的范德华超晶格中逐层解开电子态。
Layer-by-layer material engineering has produced interesting quantum phenomena such as interfacial superconductivity and the quantum anomalous Hall effect. However, probing electronic states layer by layer remains challenging. This is exemplified by the difficulty in understanding the layer origins of topological electronic states in magnetic topological insulators. Here we report a layer-encoded frequency-domain photoemission experiment on the magnetic topological insulator (MnBi2Te4)(Bi2Te3) that characterizes the origins of its electronic states. Infrared laser excitations launch coherent lattice vibrations with the layer index encoded by the vibration frequency. Photoemission spectroscopy then tracks the electron dynamics, where the layer information is carried in the frequency domain. This layer–frequency correspondence shows wavefunction relocation of the topological surface state from the top magnetic layer into the buried second layer, reconciling the controversy over the vanishing broken-symmetry energy gap in (MnBi2Te4)(Bi2Te3) and its related compounds. The layer–frequency correspondence can be harnessed to disentangle electronic states layer by layer in a broad class of van der Waals superlattices.