• DOI:10.1038/s41567-019-0692-4
• Corpus ID: 159041365

Interacting topological edge channels

@article{Strunz2019InteractingTE,
  title={Interacting topological edge channels},
  author={Jonas Strunz and Jonas Wiedenmann and Christoph Fleckenstein and Lukas Lunczer and Wouter Beugeling and Valentin L M{\"u}ller and Pragya Shekhar and Niccol{\`o} Traverso Ziani and Saquib Shamim and Johannes Kleinlein and Hartmut Buhmann and Bjorn Trauzettel and Laurens W. Molenkamp},
  journal={Nature Physics},
  year={2019},
  volume={16},
  pages={83-88}
}

• Jonas Strunz, J. Wiedenmann, +10 authors L. Molenkamp
• Published 20 May 2019
• Physics
• Nature Physics

Electrical currents in a quantum spin Hall insulator are confined to the boundary of the system. The charge carriers behave as massless relativistic particles whose spin and momentum are coupled to each other. Although the helical character of those states is already established by experiments, there is an open question regarding how those edge states interact with each other when they are brought into close spatial proximity. We employ an inverted HgTe quantum well to guide edge channels from opposite sides of a device into a quasi-one-dimensional constriction. Our transport measurements show that, apart from the expected quantization in integer steps of 2 e 2 / h , we find an additional plateau at e 2 / h . We combine band structure calculations and repulsive electron–electron interaction effects captured within the Tomonaga–Luttinger liquid model and Rashba spin–orbit coupling to explain our observation in terms of the opening of a spin gap. These results may have direct implications for the study of one-dimensional helical electron quantum optics, and for understanding Majorana and para fermions. Little is known about how edge states in topological materials interact with each other. Here, a quantum spin Hall insulator is used to show that when edge states are brought close together, additional gaps appear in the spectrum.