Zang Yunyi, Küster Felix, Zhang Jibo, Liu Defa, Pal Banabir, Deniz Hakan, Sessi Paolo, Gilbert Matthew J, Parkin Stuart S P
Max Planck Institute of Microstructure Physics, Halle 06120, Germany.
University of Illinois at Urbana-Champaign, Department of Electrical and Computer Engineering, Urbana, Illinois 61820, United States.
Nano Lett. 2021 Apr 14;21(7):2758-2765. doi: 10.1021/acs.nanolett.0c04648. Epub 2021 Apr 1.
Artificially engineered topological superconductivity has emerged as a viable route to create Majorana modes. In this context, proximity-induced superconductivity in materials with a sizable spin-orbit coupling has been intensively investigated in recent years. Although there is convincing evidence that superconductivity may indeed be induced, it has been difficult to elucidate its topological nature. Here, we engineer an artificial topological superconductor by progressively introducing superconductivity (Nb), strong spin-orbital coupling (Pt), and topological states (BiTe). Through spectroscopic imaging of superconducting vortices within the bare -wave superconducting Nb and within proximitized Pt and BiTe layers, we detect the emergence of a zero-bias peak that is directly linked to the presence of topological surface states. Our results are rationalized in terms of competing energy trends which are found to impose an upper limit to the size of the minigap separating Majorana and trivial modes, its size being ultimately linked to fundamental materials properties.
人工工程拓扑超导已成为创造马约拉纳模式的可行途径。在此背景下，近年来人们对具有可观自旋轨道耦合的材料中的近邻诱导超导进行了深入研究。尽管有令人信服的证据表明超导确实可以被诱导出来，但阐明其拓扑性质一直很困难。在这里，我们通过逐步引入超导性（铌）、强自旋轨道耦合（铂）和拓扑态（碲化铋）来设计一种人工拓扑超导体。通过对裸波超导铌以及近邻铂和碲化铋层内的超导涡旋进行光谱成像，我们检测到一个零偏置峰的出现，该峰与拓扑表面态的存在直接相关。我们的结果根据相互竞争的能量趋势得到了合理的解释，这些能量趋势被发现对分隔马约拉纳模式和平凡模式的小能隙大小施加了上限，其大小最终与基本材料特性相关。
