# WS₂ layers show nonlinear phase changes in electron ptychography

> Researchers compared monolayer, bilayer and trilayer regions of WS₂ in one specimen using electron ptychography. The measured phase of tungsten columns rose about 13.2% from one to two layers, but only 4.7% from two to three.

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- Section: Science
- Country: China
- Published: 2026-10-13T01:40:12+00:00
- Updated: 2026-10-13T01:40:12+00:00
- Source review period: 2026-10-09
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The phase reconstructed from diffraction patterns recorded as an electron probe scans a sample can reveal atomic-scale electrostatic potential. Its interpretation is affected by specimen thickness, multiple scattering and overlap between projected atomic columns. The team used different thickness regions in a twisted trilayer WS₂ specimen as an internal reference within the same field of view.

Mean tungsten-column phase rose about 13.2% from the monolayer region to the bilayer, but only 4.7% from the bilayer to the trilayer. Short-range projected W-W overlap added roughly 8–9%, while W-S overlap had little effect. The measurements show that phase does not simply rise linearly with layer count and provide a benchmark for interpreting phase-based potential maps.

## Data

### Measurements reported by the study

The table reports only findings within this study’s experimental or model scope.

Methodology: Quantity and scope are taken from the methods and results of the first arXiv version dated 9 October 2026; they should not be generalized beyond the study.

| Reported study quantity | Value | Study-specific scope |
|---|---|---|
| Approximate increase in mean W-column phase from monolayer to bilayer | 13.2 | Approximate relative change measured under the same acquisition and reconstruction conditions in one specimen; it is not a linear increase with layer count. |
| Increase in mean W-column phase from bilayer to trilayer | 4.7 | Relative increase measured in the same specimen under the same conditions; short-range projected W-W overlap can also affect phase. |

Sources: <https://arxiv.org/abs/2610.13115> · Download data: [JSON](https://newsverum.com/api/v1/articles/ptychography-ws2-thickness-nonlinear-phase-response-2026/data/study-measurements?lang=en&format=json) · [CSV](https://newsverum.com/api/v1/articles/ptychography-ws2-thickness-nonlinear-phase-response-2026/data/study-measurements?lang=en&format=csv)

## Sources

- [arXiv](<https://arxiv.org/abs/2610.13115>) (Source checked: 2026-10-13; Published: 2026-10-09)

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