High-resolution potential imaging using the Atomic SET - Part I

Visualizing electronic states on local scales is becoming an essential tool to understand new quantum states of matter. One central property that can be visualized is electrostatic potential. Its measurement enables local imaging of a variety of key thermodynamic quantities including electronic compressibility, magnetization, and entropy. To date, the best scanning detector of electrostatic potential is the scanning single electron transistor (SET). Its ability to measure on microscopic scales has allowed it to evade disorder prevalent in many quantum materials and unearth exciting new phenomena. However, existing scanning SETs have a critical limitation – with a spatial resolution of ~100 nm, they cannot access the growing list of charge-ordered quantum states that appear on ~10 nm scales, e.g. in moiré lattices. Here, we will showcase a novel scanning probe that improves SET spatial resolution by two orders of magnitude, down to 1 nm. Based on the quantum twisting microscope (QTM), it uses a single atomic defect embedded in a pristine van der Waals interface as the smallest scanning detector of electrostatic potentials. In Part I, I will present the operating principle of this novel probe and how its different modalities expand our toolset for understanding quantum materials.