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Title: What carries Landau quantization in insulating monolayer WTe2?
Plain: 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: 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.
Settled by: Simultaneous thermodynamic (capacitance, magnetization) and transport oscillation measurements versus gate density, with local probes showing whether a Fermi surface of charged carriers is present.
Kind: well-posed
Answer type: identification
References: (empty)
Literature status: open
Status note: Sign-alternating thermopower oscillations in the insulating state were reported in 2024 (Tang et al., arXiv 2405.09665).
Posed since: 2021