STM studies of air-sensitive WTe₂ enabled by sliding disassembly techniques

Tungsten ditelluride (WTe₂) in the 1T’ crystal phase exhibits an intriguing range of electronic behavior, including a quantum spin Hall insulator at charge neutrality and superconductivity upon electron doping. A key open question is the origin of the topological gap at charge neutrality. Temperature-dependent transport measurements suggest an excitonic condensate arising from overlapping electron and hole-like Fermi pockets, though this mechanism remains uncertain. Direct measurements of the gapped electronic spectrum as a function of doping are crucial to resolving this question, and scanning tunneling microscopy (STM) provides this information with sub-nanometer spatial resolution. However, STM studies of gated WTe₂ are limited by its extreme air-sensitivity. Here we present our measurements of surface-exposed gate-tunable WTe₂ devices fabricated using a novel sliding disassembly approach, in which sample fabrication is performed in an inert glovebox environment without exposing WTe₂ to solvents or transfer polymers. Using this technique, we observe topographic and spectroscopic features consistent with prior STM studies of WTe₂. Notably, we detect a gap-like feature at charge neutrality whose width evolves continuously with doping, a behavior previously attributed to a correlated many-body gap. Our results establish sliding disassembly as a new route to state-of-the-art STM measurements of ultra-air-sensitive materials.