Observation of a Majorana zero mode in a topologically protected edge channel

• Published in: Science (American Association for the Advancement of Science) Vol. 364; no. 6447; pp. 1255 - 1259
• Main Authors: Jäck, Berthold, Xie, Yonglong, Li, Jian, Jeon, Sangjun, Bernevig, B. Andrei, Yazdani, Ali
• Format: Journal Article
• Language: English
• Published: United States American Association for the Advancement of Science 28.06.2019; The American Association for the Advancement of Science; American Association for the Advancement of Science (AAAS)
• Subjects: Bismuth; Clusters; Heterostructures; Iron; Magnetism; Niobium; Protective coatings; RESEARCH ARTICLE; Scanning tunneling microscopy; Spectroscopy; Substrates; Superconductivity; Topological insulators; Topology
• ISSN: 0036-8075; 1095-9203; 1095-9203
• DOI: 10.1126/science.aax1444

Superconducting proximity pairing in helical edge modes, such as those of topological insulators, is predicted to provide a unique platform for realizing Majorana zero modes (MZMs). We used scanning tunneling microscopy measurements to probe the influence of proximity-induced superconductivity and magnetism on the helical hinge states of bismuth(111) films grown on a superconducting niobium substrate and decorated with magnetic iron clusters. Consistent with model calculations, our measurements revealed the emergence of a localized MZM at the interface between the superconducting helical edge channel and the iron clusters, with a strong magnetization component along the edge. Our experiments also resolve the MZM’s spin signature, which distinguishes it from trivial in-gap states that may accidentally occur at zero energy in a superconductor.