What carries Landau quantization in insulating monolayer WTe2?
In plain words
Monolayer WTe2, an insulator in its interior, shows resistance oscillations starting at a weak magnetic field, as if it contained very mobile particles. What these particles are is unknown.
Precise statement
In gated monolayer WTe2 near charge neutrality, where the bulk is insulating (a 2D topological insulator, also proposed as an excitonic insulator), resistance oscillates periodically in $1/B$ from an onset of $\sim 5e3\,\mathrm{G}$ (Wang et al. 2021), and thermopower oscillates with sign changes (2024). Identify the mobile fermions responsible (neutral fermions, excitons, or charged carriers of a hidden Fermi surface) and explain why oscillations appear while the bulk resistance stays large.
What would settle it
Simultaneous thermodynamic (capacitance, magnetization) and transport oscillation measurements versus gate density, with local probes showing whether a Fermi surface of charged carriers is present.
Status in the literature
Unverified note
Sign-alternating thermopower oscillations in the insulating state were reported in 2024 (Tang et al., arXiv 2405.09665).