日本理研研究所Minoru Kawamura课题组揭示了量子反常霍尔绝缘体中的劳克林电荷泵送。相关论文于2023年1月19日发表于国际顶尖学术期刊《自然—物理学》杂志上。

课题组研究人员报告了在拓扑绝缘体的薄膜磁异质结构中电荷泵浦的观察，其几何形状禁止边缘输运。课题组人员发现当样品处于量子反常霍尔绝缘体相时，在交变磁场的作用下，内外电极之间发生了电荷泵浦现象。泵送电荷的数量由每个表面的霍尔电导率为量子电导的一半来解释，从与轴子绝缘体相的比较来看，没有电荷泵送。由于电荷泵浦与理论预测的拓扑磁电效应密切相关，他们的观测可能为其直接观测提供线索。

据了解，绝热电荷抽运是物质拓扑相最显著的特征之一。量子霍尔系统中的劳克林电荷泵浦是一个典型的例子。作为类比，三维拓扑绝缘体已被预测支持电荷泵浦通过其磁隙表面状态。但是，尽管电荷泵浦作为表面霍尔电导率的直接探测很重要，但它还没有在基于拓扑绝缘体的系统中得到证明。

附：英文原文

Title: Laughlin charge pumping in a quantum anomalous Hall insulator

Author: Kawamura, Minoru, Mogi, Masataka, Yoshimi, Ryutaro, Morimoto, Takahiro, Takahashi, Kei S., Tsukazaki, Atsushi, Nagaosa, Naoto, Kawasaki, Masashi, Tokura, Yoshinori

Issue&Volume: 2023-01-19

Abstract: Adiabatic charge pumping is one of the most salient features of topological phases of matter1,2,3. Laughlin’s charge pumping in a quantum Hall system is the prototypical example4. In analogy, three-dimensional topological insulators have been predicted to support charge pumping through their magnetically gapped surface states5,6,7,8,9,10. But despite its importance as a direct probe of surface Hall conductivity, charge pumping has not been demonstrated in topological-insulator-based systems. Here we report the observation of charge pumping in a thin-film magnetic heterostructure of topological insulators in a geometry that prohibits edge transport. We find that charge pumping occurs between the inner and outer electrodes in response to alternating magnetic fields when the sample is in the quantum anomalous Hall insulator phase. The amount of pumped charge is accounted for by the surface Hall conductivity of half the quantum conductance for each surface, from a comparison with the axion insulator phase that shows no charge pumping. Because charge pumping is closely related to the theoretically predicted topological magnetoelectric effect5,6,7,8,9,10, our observation may provide clues to its direct observation.

DOI: 10.1038/s41567-022-01888-2

Source: https://www.nature.com/articles/s41567-022-01888-2