Yes, topological insulators do exist

Do topological insulators—substances that act like insulators on the inside but whose surface contains conducting states—really exist? It would appear so based on experiments conducted on quantum wells just a few nanometers thick, but the findings are difficult to apply to three-dimensional objects. However, now a CNRS-Leti research team has discovered these surprising properties on a sample they created that is several tens of nanometers thick.
This research will be developed further under a new project called Semitopo, to be funded by the French National Research Agency. Semitopo will focus on the characterization and optimization of these first “made in Grenoble” topological insulators; the Synchrotron will be used to take measurements.
The topological insulators are made of constrained layers of mercury telluride deposited on cadmium telluride substrates. The first challenge was to make the insulators; Leti had to draw on its 30 years’ experience in molecular beam epitaxy, a process developed—and continually being improved—for Sofradir infrared imaging systems. Scientists at Institut Néel then characterized the insulators using transport measurements.
The study of topical insulators also has applications in applied research. Since they are able to carry a spin current without a magnetic effect, they can be used to make spintronics and, eventually, quantum computers.

Contact: philippe.ballet@cea.fr

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