Finnish team creates long-predicted 2D quantum insulator
Researchers made a two-layer tin telluride material and observed strain-controlled edge conduction, according to a Nature Communications study.
By Tom Brennan · Health & Medicine Correspondent
3 min read
Physicists in Finland have made a two-dimensional topological crystalline insulator that had been predicted for more than 10 years, the University of Jyväskylä said. The result matters because the material’s edge conduction can be controlled by strain, a property researchers say could help future quantum and spin-based electronics.
The work was carried out by researchers at the University of Jyväskylä and Aalto University and published in Nature Communications. According to the university, the project was led by Associate Professor Kezilbeiek Shawulienu, with Aalto University researchers including professors Peter Liljeroth and Jose Lado.
The team created the material by growing an atomically thin film of tin telluride, or SnTe, on a niobium diselenide substrate. The film was made of two layers, giving researchers a platform thin enough to test the predicted two-dimensional topological behavior.
Edge states confirmed
To build and examine the material, the researchers used molecular beam epitaxy and low-temperature scanning tunneling microscopy, according to the University of Jyväskylä. Those methods allowed them to study the film’s electronic properties at atomic-scale resolution.
The measurements showed pairs of conducting edge states, which the university described as a key signature of topological crystalline insulators. In these materials, electrons can move along the edges, and the conducting channels are protected by the symmetry of the crystal lattice.
The edge states were found inside an electronic band gap of more than 0.2 electron volts, according to the study summary. The university said that relatively large gap is one reason the material’s topological properties are expected to persist at room temperature.
Strain provides a control knob
The researchers found that the niobium diselenide substrate compresses the tin telluride film. According to the university, that strain plays an essential role in stabilizing the topological state observed in the two-layer material.
The team also showed that changing the strain can adjust the conducting edge states. The University of Jyväskylä said that tunability gives researchers a practical way to control the material’s electronic behavior, a requirement for possible device uses.
First-principles quantum mechanical calculations supported the conclusion that the edge states have a topological origin, according to the research report. The team also studied interactions between nearby edge states and found that their energy levels shift because of electrostatic interactions and quantum tunneling.
The university said the result offers a platform for studying strain-tunable, two-dimensional topological states. Researchers also point to possible applications in nanoscale devices and spin-based electronics, though the findings reported so far concern material creation and measurement rather than a working device.
The paper, “Strain-induced two-dimensional topological crystalline insulator in bilayer SnTe,” was published in Nature Communications. The listed authors are Liwei Jing, Mohammad Amini, Adolfo O. Fumega, Orlando J. Silveira, Jose L. Lado, Peter Liljeroth and Shawulienu Kezilebieke; the DOI is 10.1038/s41467-025-67520-y.
This story draws on original reporting from ScienceDaily.