For more than ten years, physicists around the world had been dreaming about it on paper but nobody could actually build it. Then a team at two Finnish universities finally did it — a special quantum material made of just two thin layers of tin and tellurium that lets electricity flow perfectly along its edges, no resistance, no energy lost.
Researchers from the University of Jyväskylä and Aalto University in Finland created what is called a two-dimensional topological crystalline insulator. Scientists had predicted this material should exist since around 2012, but growing it in a lab proved incredibly tricky. The breakthrough came when the team, led by Associate Professor Kezilbeiek Shawulienu alongside Professor Peter Liljeroth and Professor Jose Lado, figured out how to grow an atomically thin film — just two layers of tin telluride — on top of a niobium diselenide surface.
To study the material, the researchers used a technique called molecular beam epitaxy, which basically lets scientists build materials one atom at a time. They then examined it with extremely cold microscopes that can see things at the atomic level. What they found matched exactly what theory had predicted: electrons flowed freely along the edges of the material, protected by the crystal's own symmetry.
One key discovery was that the substrate underneath the tin telluride creates strain — a kind of controlled squeezing — that stabilizes the material's special quantum properties. The band gap, which is essentially the energy window where these quantum states exist, measured more than 0.2 electron volts. That might sound small, but it's large enough that the material could potentially work at room temperature, which is a big deal for practical applications.
The team also showed that changing how much the material is stretched or squeezed can actually control those edge states. That means engineers could someday tune the material for different uses, like faster computers or tiny devices that waste almost no energy.
The findings, published in the journal Nature Communications, open up new possibilities for what are called spin-based electronics — a technology that uses not just the electron's charge but also its spinning motion to process information. The Finnish team believes their work could eventually support advances in nanoscale devices that are faster, smaller, and more efficient than anything we have today.