Visualizing interaction-driven restructuring of quantum Hall edge states
Summary
Researchers used high-resolution scanning tunnelling microscopy and spectroscopy (STM/STS) on gate-defined graphene to directly image how electron interactions reshape quantum Hall edge channels. The team mapped valley polarisation, intervalley coherence and isospin textures at the atomic scale and demonstrated that the steepness of the edge potential can tune edge reconstruction — merging or splitting channels and driving an edge spin phase transition. The observations are supported by theoretical modelling and data are available on Figshare.
Key Points
- Atomic-scale STM/STS imaging captures the internal structure of quantum Hall edge channels in graphene.
- Edge states show measurable valley polarisation and intervalley coherence, revealed via FFT and iFFT analysis of STS maps.
- The steepness of the gate-defined edge potential controls whether four co-propagating channels remain distinct or merge into two — a tunable edge reconstruction.
- Isospin (valley + spin) measurements indicate a potential-driven spin phase transition at the edge.
- The findings reconcile microscopic imaging with theoretical predictions for interaction-driven edge restructuring.
- Data supporting the paper are publicly available at figshare (DOI provided in the original article).
- Work combines experiment (Princeton, UCSB) with detailed theoretical calculations (UC Berkeley) and is peer-reviewed in Nature.
Content summary
The paper presents STS maps across gate-defined, L-shaped graphene edges under quantum Hall conditions to trace Landau-level shifts and identify resonant tunnelling peaks. Fourier analysis of atomic-scale maps isolates Bragg and Kekul\u00e9-related features; inverse FFT reveals sublattice-resolved valley polarisation. By varying gate voltages and edge potential steepness, the authors observe controllable reconstruction: in smoother potentials four distinct flavours appear, while steeper potentials drive pairs to merge, changing spin-polarisation patterns. Theory calculations reproduce the qualitative behaviour and support interpretation in terms of interaction-driven isospin energetics.
Context and relevance
This work sits at the intersection of topological quantum matter and nanoscale imaging. Edge-state structure is central to quantum Hall transport, interferometry and proposals for topological qubits; direct visualisation of interaction-driven restructuring helps explain puzzling transport phenomena and guides device engineering. The results also tie into a suite of recent advances (atomic-scale imaging of edge currents, broken-symmetry orders in graphene, anyon experiments) that together push our microscopic understanding of quantum Hall edges.
Author style
Punchy: This is a high-impact, well-supported experiment that actually looks under the bonnet of quantum Hall edges. If you work on topological transport, graphene devices or edge-based interferometry, the detailed images and the tunable reconstruction story are worth digging into — theory and data are both provided.
Why should I read this?
Quick and casual: fancy pictures of edge states, clear proof that interactions can rewire channels at the edge, and a neat knob (edge potential steepness) to switch behaviour. If you care about how microscopic edge structure affects transport, interference or anyon experiments, this saves you time — read it.
Source
Source: https://www.nature.com/articles/s41586-025-09858-3
Article metadata
Published: 17 December 2025. Corresponding author: Ali Yazdani (yazdani@princeton.edu). Data: https://doi.org/10.6084/m9.figshare.30456452. Peer review reports available on Nature’s site.