For decades, physicists have sought a practical two-dimensional topological insulator: an ultrathin material whose interior blocks electricity but whose edges conduct it. In ordinary wires, electrons constantly bounce off imperfections, losing energy. But along the edges of a 2D topological insulator, electrons with opposite spins travel in opposite directions, like cars in one-way lanes, so they rarely scatter and lose energy.
Now, researchers at the University of Chicago Pritzker School of Molecular Engineering (UChicago PME) have shown that ultrathin films of bismuth telluride are such a material. The work, published in ACS Nano, used a new approach to produce a uniform-thickness bismuth telluride film and confirm theoretical predictions about the material's properties.
"In a strict scientific sense, we are the first to demonstrate conclusive spectroscopic evidence that this is indeed a 2D topological insulator," said Shuolong Yang, assistant professor of molecular engineering at UChicago PME and senior author of the new work. "When people created these films in the past, they were all mixed up with one, two, three or four layers, and the topological electronic properties weren't resolved."
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