Visualizing the in-gap states in domain boundaries of ultra-thin topological insulator films

Abstract

Ultra-thin topological insulators provide a platform of realizing many exotic phenomena such a Quantum spin Hall effect, Quantum anomalous Hall effect, etc. These effects or states are characterized by quantized transport behavior of edge states. Experimentally, although these states have been realized in various systems, the temperature for the edge states to be the dominating channel in transport is extremely low, contrary to the fact that the bulk gap is usually in the order of a few tens of milli-electron volts. There must be other in-gap conduction channels that won't freeze out till a much low temperature. Here we grow ultra-thin topological insulator Bi2Te3 and Sb2Te3 films by molecular beam epitaxy and investigate the structures of domain boundaries in these films. By scanning tunneling microscopy and spectroscopy we find that the domain boundaries with large rotation angles have pronounced in-gap bound states, through which one dimensional conduction channels are suggested to form as visualized by spatially resolved spectroscopy. Our work indicates the critical role played by domain boundaries in degrading the transport properties.

arXiv comment10 pages, 4 figures

References in corpus (18)

• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• Quantum Spin Hall Insulator State in HgTe Quantum Wells
• Experimental Observation of the Quantum Anomalous Hall Effect in a Magnetic Topological Insulator
• Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class with spin-polarized single-Dirac-cone on the surface
• Quantized Anomalous Hall Effect in Magnetic Topological Insulators
• Grains and grain boundaries in highly crystalline monolayer molybdenum disulfide
• Quantum Spin Hall Effect and Topological Field Effect Transistor in Two-Dimensional Transition Metal Dichalcogenides
• Magnetic-field-induced quantized anomalous Hall effect in intrinsic magnetic topological insulator MnBi${}_2$Te${}_4$
• Evidence for Helical Edge Modes in Inverted InAs/GaSb Quantum Wells
• High-precision realization of robust quantum anomalous Hall state in a hard ferromagnetic topological insulator
• Observation of the Quantum Spin Hall Effect up to 100 Kelvin in a Monolayer Crystal
• Quantum Spin Hall Effect in Inverted Type II Semiconductors
• Experimental realization of an intrinsic magnetic topological insulator
• Oscillatory crossover from two dimensional to three dimensional topological insulators
• Quintuple-layer epitaxy of high-quality Bi2Se3 thin films for topological insulator
• Landau quantization and the thickness limit of topological insulator thin films of Sb2Te3
• Topological insulator Bi2Se3 thin films grown on double-layer graphene by molecular beam epitaxy
• Characterizing the Structure of Topological Insulator Thin Films