Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
TT: Fachverband Tiefe Temperaturen
TT 50: Superconductivity: Theory II
TT 50.11: Vortrag
Mittwoch, 20. März 2024, 17:45–18:00, H 3005
Topological edge and corner states in Bi fractals on InSb — •Robert Canyellas1,2, Chen Liu3, R. Arouca4, L. Eek1, Guanyong Wang3, Yin Yin3, Dandan Guan3,5, Yaoyi Li3,5, Shiyong Wang3,5, Hao Zheng3,5, Canhua Liu3,5, Jinfeng Jia3,5, and C. Morais Smith1 — 1Institute for Theoretical Physics, Utrecht University, Princetonplein 5, 3584CC Utrecht, The Netherlands — 2Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525AJ Nijmegen, The Netherlands — 3Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China — 4Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden — 5Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
Topological materials hosting metallic edges characterized by integer quantized conductivity in an insulating bulk have revolutionized our understanding of transport in matter. The topological protection of these edge states is based on symmetries and dimensionality. However, only integer-dimensional models have been classified, and the interplay of topology and fractals, which may have a non-integer dimension, remained largely unexplored. Quantum fractals have recently been engineered in metamaterials, but up to present no topological states were unveiled in fractals realized in real materials. Here, we show theoretically and experimentally that topological edge and corner modes arise in fractals formed upon depositing thin layers of bismuth on an indium antimonide substrate. Scanning tunneling microscopy reveals the appearance of (nearly) zero-energy modes at the corners of Sierpiński triangles, as well as the formation of outer and inner edge modes at higher energies. Unexpectedly, a robust and sharp depleted mode appears at the outer and inner edges of the samples at negative bias voltages. The experimental findings are corroborated by theoretical calculations in the framework of a continuum muffin-tin and a lattice tight-binding model. The stability of the topological features to the introduction of a Rashba spin-orbit coupling and disorder is discussed. This work opens the perspective to novel electronics in real materials at non-integer dimensions with robust and protected topological states.
Keywords: Fractals; Superconductivity