Topological insulators represent a class of quantum materials exhibiting a host of unique physical properties. As an important category of topological insulators, quantum spin Hall insulators show one-dimensional topological helical edge states. Here, we report the successful growth of the high-quality ultrathin ${\mathrm{Bi}}_2{\mathrm{Te}}_3$ film on a Nb-doped ${\mathrm{SrTiO}}_3$(001) substrate by molecular beam epitaxy. With a ${\mathrm{Bi}}_2{\mathrm{Te}}_3$ island around one quintuple layer higher than the three quintuple layer thick film, one-dimensional edge states between even and odd quintuple layers (i.e., between the island and the film) are directly observed by scanning tunneling microscopy and spectroscopy. Combined with theoretical prediction, our work provides the signature of the existence of the quantum spin Hall phase in ultrathin ${\mathrm{Bi}}_2{\mathrm{Te}}_3$ film, and offers a platform for exploring one-dimensional helical edge states and related quantum devices.

Close

PrevNext

View figure in article

• Density of states
• Edge states
• Geometric & topological phases
• Topological insulators
• 2-dimensional systems
• Thin films
• Topological materials
• Atomic force microscopy
• Molecular beam epitaxy
• Scanning tunneling microscopy
• Scanning tunneling spectroscopy