Zero-field edge conductance limitation in 2D topological insulators

Determine what mechanism(s) limit the edge conductance at zero magnetic field in monolayer WTe2 and other two-dimensional topological insulators, despite single-particle backscattering being forbidden by time-reversal symmetry, to enable robust edge transport for applications.

Background

Monolayer WTe2 exhibits the expected characteristics of a two-dimensional topological insulator, including edge-localized conduction and suppression of backscattering protected by time-reversal symmetry. Nevertheless, experiments show that edge conduction diminishes with increasing edge length and freezes out below a few kelvin, indicating unknown limiting mechanisms.

Understanding and mitigating these limits is central to realizing practical devices that exploit helical edge modes for low-power electronics and quantum information technologies.

References

The most obvious open question, applicable to all 2DTIs and key to potential applications, is what limits the edge conductance at zero magnetic field where single-particle backscattering is prohibited.

— 2024 roadmap on 2D topological insulators  (2406.14209 - Weber et al., 2024) in Section 3.2 (Tungsten Ditelluride), Current and Future Challenges, Page 21

In spite of extensive theoretical work, the origin of the unexpectedly low mobility of edge states in TIs with strong SOI and band inversion remains unresolved.

— Quantum oscillations of helical edge states of periodically deformed 2D topological insulator in magnetic field  (2609.04359 - Tsvetkova et al., 3 Sep 2026) in Section 1, Introduction