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Topological insulator functions at room temperature

A topological insulator that can function at room temperature had been developed by physicists from the University of Wuerzburg.

According to the researchers, all known topological insulators have to be cooled to very low temperatures – usually -270°C – to study the quantum properties of the edge channels.

"As the temperature of a topological insulator increases, all quantum effects are washed out and with them the special properties of the electrically conducting edges," Dr Jörg Schäfer explains.

"Of course, such conditions are not very practicable for potential applications such as ultra-fast electronics or quantum computers.”

To solve this problem, the physicists used a special combination of materials: an ultra-thin film consisting of a single layer of bismuth atoms deposited on a silicon carbide substrate.

"The crystalline structure of the silicon carbide substrate causes the bismuth atoms to arrange in a honeycomb geometry when depositing the bismuth film – very similar to the structure of the 'miracle material' graphene," Professor Ralph Claessen explains.

Because of this analogy, the waver-thin film is called ‘bismuthene’.

"Bismuthene forms a chemical bond to the substrate," said Professor Ronny Thomale. "Whereas common bismuth is an electrically conductive metal, the honeycomb monolayer remains a distinct insulator, even at room temperature and far above.”

The metallic electronic conduction channels which could be used for future data processing are located at the edge of the bismuthene.

"Such conduction channels are 'protected topologically'. This means they can be used to transmit information virtually without loss," Ralph Claessen says.

This approach could enable spintronics, according to the scientists.

Peggy Lee

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