Local Characterization of Correlated States in an MoTe₂ Twisted Bilayer Moiré Superlattice

Moiré superlattices in transition metal dichalcogenides (TMDs) host a variety of exotic quantum phenomena, such as generalized Wigner crystals, the integer quantum anomalous Hall (QAH) effect, and fractional Chern insulators (FCIs). These topological and correlated phenomena are often accompanied by electronic states having novel signatures at the moiré length-scale that are difficult to probe with conventional optical or transport methods. We have used scanning tunneling microscopy/spectroscopy (STM/S) to examine the local electronic states in gate-tunable twisted MoTe₂ (t-MoTe₂) devices. Our samples include a Si/SiO₂ back gate under the t-MoTe₂ and a monolayer graphene/ hBN sensing layer above the t-MoTe₂ that allow us to separately control the carrier density and electric field in the t-MoTe₂ [1] and to detect the formation of insulating states in t-MoTe₂ through charging/discharging events in the graphene sensing layer [2]. We have performed spectroscopic characterization of t-MoTe₂ at different filling levels and electric fields to locally probe novel correlated and topological states observed previously in optical and transport measurements.

[1] H. Li et al., Nature 597, 650 (2021).

[2] H. Li et al., ArXiv: 2209.12830 (2022).