近日，美国波士顿学院Ma, Qiong团队研究了量子自旋霍尔绝缘体中的双稳态超晶格开关。2026年3月18日出版的《自然》杂志发表了这项成果。

双稳态开关通常源于铁电性和铁磁性等铁性序，其双稳态由电荷或自旋自由度编码。

研究组报告在单层TaIrTe4（一种双量子自旋霍尔绝缘体）中观测到的双稳态超晶格开关现象。开关过程发生在两种晶格构型之间，这两种构型具有截然不同的周期特性。值得注意的是，在原始单层中，研究组观测到长周期超晶格的自发形成，通过静电调控低能电子态可实现对超晶格的非易失性开关操作。这种开关使体系在两种晶胞面积相差两个数量级的结构构型间切换。机理研究表明，体系存在两个独立且不同的不稳定性——分别源于晶格本身和量子自旋霍尔电子。

这两种不稳定性相互耦合，从而实现对晶格构型的静电调控并形成非易失性存储。该发现得益于线性与非线性输运测量、拉曼光谱和扫描隧道显微镜的联合应用，这些技术从不同维度探测了潜在序的互补特征。值得注意的是，这种非易失性存储器稳定了周期为几纳米的自发超晶格，该结构在宽掺杂范围内保持稳定，可持续数天并耐受70K以上温度。初步数据还显示，在超晶格分数量子态填充时出现了新型绝缘态，且该绝缘态可随超晶格同步开关。

附：英文原文

Title: Bistable superlattice switching in a quantum spin Hall insulator

Author: Tang, Jian, Ding, Thomas Siyuan, Ding, Shuhan, Li, Jiangxu, Yi, Changjiang, Tang, Tianxing, Huang, Zumeng, Wu, Xuehao, Huang, Zhiheng, Singh, Birender, Qian, Tiema, Belosevich, Vsevolod, Guo, Mingyang, Gao, Anyuan, Peshcherenko, Nikolai, Sun, Zhe, Shehabeldin, Mohamed, Watanabe, Kenji, Taniguchi, Takashi, Pasupathy, Abhay N., Felser, Claudia, S. Burch, Kenneth, Ni, Ni, Wang, Yao, Zhang, Yang, Xu, Su-Yang, Ma, Qiong

Issue&Volume: 2026-03-18

Abstract: Bistable switching typically arises from ferroic orders, such as ferroelectricity and ferromagnetism, in which the bistable states are encoded in charge or spin degrees of freedom1,2. Here we report the observation of bistable superlattice switching in monolayer TaIrTe4, a dual quantum spin Hall insulator3,4,5. Switching occurs between two lattice configurations with sharply contrasting periodicities. In particular, in a pristine monolayer, we observe the spontaneous emergence of a long-period superlattice that can be programmed on and off in a non-volatile manner by electrostatic tuning of low-energy electronic states. This switching toggles the system between two structural configurations with unit cell areas differing by two orders of magnitude. Mechanistically, our results reveal two independent and distinct instabilities, one in the lattice and the other in the quantum spin Hall electrons. These instabilities are coupled, leading to electrostatic control of lattice configurations with non-volatile memory. This finding is enabled by combining linear and nonlinear transport measurements6,7,8,9,10,11,12,13, Raman spectroscopy and scanning tunnelling microscopy, which probe complementary aspects of the underlying orders. Notably, this non-volatile memory stabilizes a spontaneous superlattice with a periodicity on the few-nanometre scale that remains robust across a wide doping range, persists over days and survives above 70K. Our preliminary data also show the emergence of new insulating states at fractional superlattice fillings, which can be switched on and off together with the superlattice.

DOI: 10.1038/s41586-026-10309-w

Source: https://www.nature.com/articles/s41586-026-10309-w