Imaging the sub-moiré potential using an atomic single electron transistor
Article Date: 04 February 2026
Article URL: https://www.nature.com/articles/s41586-025-10085-z
Article Image: https://media.springernature.com/lw685/springer-static/image/art%3A10.1038%2Fs41586-025-10085-z/MediaObjects/41586_2025_10085_Fig1_HTML.png
Summary
The authors introduce the “atomic SET”: a scanning sensor that uses a single atomic defect in a thin TMD layer as a quantum-dot-like single-electron transistor. By placing the sample on the tip and scanning it across this fixed atomic defect, they achieve ≈1 nm spatial resolution and a potential sensitivity of ~5 μV Hz−1/2 — two orders of magnitude improvement in spatial resolution over conventional scanning SETs.
Using this probe on an aligned graphene/hexagonal-boron-nitride (G/hBN) tip, they directly map the moiré electrostatic potential at the G/hBN interface. Key experimental findings: the moiré potential has a large peak-to-peak amplitude (~52–62 mV), shows approximate C6 symmetry about the moiré centre, and changes only weakly (≈10%) with carrier filling. The measured potential amplitude is roughly twice that predicted by existing self-consistent theoretical models, signalling gaps in current understanding of even this paradigmatic vdW interface.
Key Points
- Technique: The atomic SET uses a single atomic defect as a quantum dot sensor, inverted geometry (sample on tip) for optimal defect selection and very small standoff distance.
- Performance: Spatial resolution ≈1 nm and potential sensitivity ≈5 μV Hz−1/2 — enough to detect minute variations in the potential from single-electron charge distributions at nanometre range.
- Direct imaging: First direct, two-dimensional maps of the electrostatic moiré potential in aligned G/hBN across a moiré unit cell at multiple fillings.
- Measured potential: Peak-to-peak amplitude ~52–62 mV at fillings including zero density; potential amplitude varies little with filling (≈10%).
- Symmetry: Maps show approximate C6 symmetry with small C3 component; theory predicts competing C3-like contributions that partially cancel to yield near-C6 symmetry.
- Theory vs experiment: Self-consistent Hartree-type calculations reproduce the potential shape but underpredict the amplitude by ~2× — suggesting incomplete modelling (strain, polarisation or other effects may be underestimated).
- Decay with height: Potential decays rapidly with distance from the interface; ultrashort standoff is essential to detect sub-moiré electrostatics.
- Implication: The atomic SET can probe thermodynamic properties and microscopic phenomena (Wigner crystals, edge states, vortex charges, fractionally charged quasiparticles) with sub-Fermi-wavelength resolution.
Why should I read this?
Short version: it’s clever and it matters. If you care about how moiré patterns actually shape electronic behaviour in 2D materials, these folks built a probe that finally shows the local potential directly — and it’s bigger than theory says. Saves you from squinting through transport or optics results; they did the hard imaging so you don’t have to.
Context and Relevance
Moiré engineering is central to many breakthroughs in van der Waals heterostructures (Hofstadter physics, correlated insulators, superconductivity, ferroelectricity, FQAHE). Until now the G/hBN moiré potential was inferred indirectly; this work provides direct, quantitative electrostatic maps at sub-moiré scales. The discrepancy between measurement and theory (≈2× larger potential) is important for modelling moiré-band engineering and for interpreting experiments that rely on assumed potential strengths (for example, fractional Chern insulators or engineered correlated phases in multilayer graphene).
Methodologically, the atomic SET’s inverted geometry and defect-based sensing open a general route to place pristine interfaces on tips and scan the interior of vdW stacks at extremely small standoffs. That offers a path to local thermodynamic and electrostatic measurements with spatial resolution below the Fermi wavelength and magnetic length, extending quantitative imaging to topological and strongly correlated phenomena that occur on the smallest length scales.