Giant magnetochiral anisotropy from quantum-confined surface states of topological insulator nanowires.
Giant magnetochiral anisotropy from quantum-confined surface states of topological insulator nanowires.
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拓扑绝缘体纳米线量子限制表面态的巨磁手征各向异性。
DOI：
10.1038/s41565-022-01124-1
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发表时间：
2022-07
影响因子：
38.3
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中科院分区：
文献类型：
--
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无线技术依赖于将交流电磁场转换为直流电，这一过程称为整流。尽管整流器通常基于半导体二极管，但最近发现了能够实现高度可控整流的量子力学非互易输运效应。其中一种效应是磁手性各向异性 (MCA)，其中材料或器件的电阻取决于电流方向和施加的磁场。然而，MCA 可能产生的整流规模通常非常小，因为 MCA 依赖于反演对称性破缺，从而导致自旋轨道耦合的表现，这是一种相对论效应。在典型材料中，MCA引起的整流系数γ通常为∣γ∣ ≲ 1 A−1 T−1（参考文献），迄今为止报道的最大值为∣γ∣ ≈ 100 A−1 T−1（碳纳米管和ZrTe5）（参考文献）。在这里，为了克服这一限制，我们通过在薄拓扑绝缘体（TI）纳米线异质结构中施加栅极电压人为地打破了反演对称性，并从理论上预测这种对称性破缺会导致巨大的MCA效应。我们的预测通过薄体绝缘 (Bi1−xSbx)2Te3 (BST) TI 纳米线的实验得到证实，其中我们观察到与理论一致的 MCA 和 ∣γ∣ ≈ 100,000 A−1 T−1，这是普通导体中非常大的 MCA 整流系数。均质材料中的非互易输运可以实现可控电流整流，但通常非常小。然而，人为打破拓扑绝缘体纳米线的反演对称性会产生巨大的磁手性各向异性校正。
Wireless technology relies on the conversion of alternating electromagnetic fields into direct currents, a process known as rectification. Although rectifiers are normally based on semiconductor diodes, quantum mechanical non-reciprocal transport effects that enable a highly controllable rectification were recently discovered. One such effect is magnetochiral anisotropy (MCA), in which the resistance of a material or a device depends on both the direction of the current flow and an applied magnetic field. However, the size of rectification possible due to MCA is usually extremely small because MCA relies on inversion symmetry breaking that leads to the manifestation of spin–orbit coupling, which is a relativistic effect. In typical materials, the rectification coefficient γ due to MCA is usually ∣γ∣ ≲ 1 A−1 T−1 (refs. ) and the maximum values reported so far are ∣γ∣ ≈ 100 A−1 T−1 in carbon nanotubes and ZrTe5 (ref. ). Here, to overcome this limitation, we artificially break the inversion symmetry via an applied gate voltage in thin topological insulator (TI) nanowire heterostructures and theoretically predict that such a symmetry breaking can lead to a giant MCA effect. Our prediction is confirmed via experiments on thin bulk-insulating (Bi1−xSbx)2Te3 (BST) TI nanowires, in which we observe an MCA consistent with theory and ∣γ∣ ≈ 100,000 A−1 T−1, a very large MCA rectification coefficient in a normal conductor. Non-reciprocal transport in a homogeneous material enables controllable current rectification, but is usually very small. Yet, artificially breaking inversion symmetry in topological insulator nanowires yields a giant magnetochiral anisotropy rectification.
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