Topology^1,2,3 and interactions are foundational concepts in the modern understanding of quantum matter. Their nexus yields three important research directions: (1) the competition between distinct interactions, as in several intertwined phases, (2) the interplay between interactions and topology that drives the phenomena in twisted layered materials and topological magnets, and (3) the coalescence of several topological orders to generate distinct novel phases. The first two examples have grown into major areas of research, although the last example remains mostly unexplored, mainly because of the lack of a material platform for experimental studies. Here, using tunnelling microscopy, photoemission spectroscopy and a theoretical analysis, we unveil a ‘hybrid’ topological phase of matter in the simple elemental-solid arsenic. Through a unique bulk-surface-edge correspondence, we uncover that arsenic features a conjoined strong and higher-order topology that stabilizes a hybrid topological phase. Although momentum-space spectroscopy measurements show signs of topological surface states, real-space microscopy measurements unravel a unique geometry of topologically induced step-edge conduction channels revealed on various natural nanostructures on the surface. Using theoretical models, we show that the existence of gapless step-edge states in arsenic relies on the simultaneous presence of both a non-trivial strong Z₂ invariant and a non-trivial higher-order topological invariant, which provide experimental evidence for hybrid topology. Our study highlights pathways for exploring the interplay of different band topologies and harnessing the associated topological conduction channels in engineered quantum or nano-devices.

拓扑^1、2、3 和相互作用是现代理解量子物质的基本概念。它们的联系产生了三个重要的研究方向：（1）不同相互作用之间的竞争，如在几个相互交织的相中，（2）驱动扭曲层状材料和拓扑磁体中现象的相互作用和拓扑之间的相互作用，以及（3）聚结几种拓扑顺序以产生不同的新相。前两个例子已经发展成为主要的研究领域，尽管最后一个例子仍然大部分未被探索，主要是因为缺乏实验研究的材料平台。在这里，我们利用隧道显微镜、光电子能谱和理论分析，揭示了简单元素固体砷中物质的“混合”拓扑相。通过独特的块体表面边缘对应关系，我们发现砷具有联合的强高阶拓扑，可以稳定混合拓扑相。尽管动量空间光谱测量显示了拓扑表面状态的迹象，但实空间显微镜测量揭示了表面各种天然纳米结构上揭示的拓扑诱导的阶跃边缘传导通道的独特几何形状。利用理论模型，我们证明砷中无间隙阶跃边缘态的存在依赖于非平凡强Z ₂不变量和非平凡高阶拓扑不变量的同时存在，这为混合拓扑提供了实验证据。我们的研究重点介绍了探索不同能带拓扑之间的相互作用以及利用工程量子或纳米器件中相关拓扑传导通道的途径。