Physicists from University of Jyväskylä and Aalto University (Finland) has realized experimentally a two-dimensional topological crystalline insulator. This is a quantum material that has been theoretically predicted for more than a decade but had remained inaccessible due to materials challenges.
Researchers realized long-sought two-dimensional topological material. The work was led by Associate Professor Kezilbeiek Shawulienu and carried out in collaboration with colleagues from Aalto University, including Professor Peter Liljeroth and Professor Jose Lado . The research team created the material by growing an atomically thin, two-layer film of tin telluride (SnTe) on a niobium diselenide (NbSe₂) substrate.
Using molecular beam epitaxy and low-temperature scanning tunneling microscopy, the researchers characterized the electronic properties of the system with atomic-scale precision. In this two-dimensional system, they observed pairs of conducting edge states, hallmarks of topological crystalline insulators, that are protected by the symmetry of the crystal lattice.
The edge states form within a large electronic band gap exceeding 0.2 eV. Measurements show that the SnTe film experiences compressive strain from the underlying substrate, which plays a crucial role in stabilizing the topological phase. Importantly, the results show that the topological edge states can be tuned by strain, providing a pathway to control their electronic properties.
First-principles quantum-mechanical calculations confirm the topological origin of the observed edge states. The researchers also directly probed interactions between neighboring edge states, revealing energy shifts driven by a combination of electrostatic interactions and quantum tunneling. Because of the large band gap, the topological properties are expected to remain robust up to room temperature.
The results provide a new experimental platform for studying strain-tunable two-dimensional topological states and may enable future advances in spin-based electronics and nanoscale devices.
The results were published in the Nature Communications .
Further information:
Nature Communications
Experimental study
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Strain-induced two-dimensional topological crystalline insulator in bilayer SnTe
21-Jan-2026