Single electron transistor microscopy of van der Waals heterostructures with displacement field tuning

Scanning probe techniques are powerful tools for imaging the local electronic behavior of quantum materials. However, a fundamental challenge is that they are often incompatible with a conventional top gate. This has hindered exploration of the complete density-displacement field (n-D) phase diagram. While a metallic tip can be used to locally tune both parameters, the result is a non-uniform electric potential, which complicates the interpretation of local electronic properties and limits the accessible parameter range. In this talk, I will discuss how we implement displacement field control in scanning single-electron transistor measurements using a van der Waals (vdW) monolayer as a top gate. We apply this approach to probe vdW heterostructures along previously unexplored trajectories in the n-D plane. The new capability paves the way for imaging the rich phase diagrams in materials including twisted transition metal dichalcogenides and rhombohedral graphene, which are known to host a variety of correlated phases, from superconductivity to integer and fractional quantum anomalous Hall states.