室温下Bi4Br4中的阶梯量子自旋霍尔态的直接可视化
Direct Visualization of Room-temperature Stair-stepped Quantum Spin Hall States in Bi4Br4
AI总结：
本研究通过微波阻抗显微镜直接可视化Bi4Br4中室温下的阶梯量子自旋霍尔态，并展示了其稳定的拓扑特性及可扩展的堆叠结构。
摘要：
拓扑绝缘体宿主了诸如量子自旋霍尔（QSH）效应等奇异量子现象，后者使耗散less的一维边缘传导成为可能。在室温下实现这种状态并在宏观尺度上实现是高效能电子和量子技术的关键，但仍然面临基本挑战，由于材料限制。在此，利用微波阻抗显微镜，我们直接可视化了α-Bi4Br4纳米线中在300K以下持续的稳健QSH状态。这种稳定性和可扩展性是由于阶梯堆叠配置，一种多层几何结构，在其中单个层的QSH边缘状态保持空间解耦。这种配置绕过了先前提案中严格对齐和层数限制的约束，允许在数微米长、数百纳米高的结构中实现稳健的阶梯QSH（SS-QSH）传导。磁场和温度依赖性测量证实了其内在拓扑性质。关键的是，SS-QSH和本征信号随纳米线高度变化，验证了阶梯起源。我们的结果也通过有限元分析模拟成功再现。这项工作确立了αBi4Br4作为高温拓扑电子学的实用平台，并展示了设计可扩展QSH系统的一般性堆叠策略。
英文摘要：
Topological insulators host exotic quantum phenomena such as the quantum spin Hall (QSH) effect, which enables dissipationless one-dimensional edge conduction. Realizing such states at room temperature and on a macroscopic scale is essential for energy-efficient electronics and quantum technologies, yet remains a fundamental challenge due to material limitations. Here, using microwave impedance microscopy, we directly visualize robust QSH states persisting up to 300 K in α-Bi4Br4 nanowires. This stability and scalability are enabled by a stair stepped stacking configuration, a multilayer geometry in which QSH edge states from individual layers remain spatially decoupled. This configuration circumvents the stringent alignment and layer number constraints of previous proposals, allowing robust stair-stepped QSH (SS-QSH) conduction in structures several micrometers long and hundreds of nanometers high. Magnetic field and temperature dependent measurements confirm their intrinsic topological nature. Crucially, the SS-QSH and bulk signals scale with nanowire height, verifying the stair stepped origin. Our results are also successfully reproduced by finite-element analysis simulations. This work establishes α Bi4Br4 as a practical platform for high temperature topological electronics and demonstrates a generalizable stacking strategy for designing scalable QSH systems.
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