Regensburg 2025 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
TT: Fachverband Tiefe Temperaturen
TT 57: Topology and Symmetry-protected Materials (joint session O/TT)
TT 57.6: Vortrag
Freitag, 21. März 2025, 11:45–12:00, H25
Revealing higher-order topological bulk-boundary correspondence in Bi crystals with spin-helical hinge state loop and proximity superconductivity — •Dongming Zhao1, Yang Zhong1, Tian Yuan1, Haitao Wang1, Tianxing Jiang1, Yang Qi1, Hongjun Xiang1,2,3, Xingao Gong1,2,3, Donglai Feng2,3,4, and Tong Zhang1,2,3,4 — 1Fudan University, Shanghai, China — 2Collaborative Innovation Center for Advanced Microstructures, Nanjing, China — 3Shanghai Research Center for Quantum Sciences, Shanghai, China — 4Hefei National Laboratory, Hefei, China
Topological materials are typically characterized by gapless boundary states, known as bulk-boundary correspondence. Recently, this concept has been generalized in higher-order topological insulators (HOTIs). E.g., a 2nd-order 3D TI hosts 1D topological hinge states winding around the crystal. A complete verification of HOTI will require probing all crystal boundaries. Here we studied a promising candidate of 2nd-order TI, Bi, in the form of mesoscopic crystals grown on superconducting V3Si. Using low-temperature STM, we directly observed dispersive 1D states on various hinges. Upon introducing magnetic scatterers, new scattering channels emerged selectively on certain hinges, revealing their spin-helical nature. Combining first-principle calculation and global symmetry analysis, we find these hinge states topological and formed a closed loop encircling the crystal. This provides direct evidence on the HOTI in Bi. Moreover, proximity superconductivity is observed in the topological hinge states serving as a promising platform for realizing topological superconductivity.
Keywords: topological materials; higher-order topological insulators; topological superconductors; proximity effect; scanning tunneling microscopy