Newly-found samples of kawazulite found in gold mines in the Czech Republic shows properties of being a topological insulator, and may in fact have a higher quality than made-made ones.
In search of materials that display these properties, Gehring and his colleagues examined a natural sample of kawazulite, which contains bismuth, tellurium, selenium and sulphur, found at a former gold mine in the Czech Republic. Lab-made samples of kawazulite have already been shown to be topological insulators, but no one had checked for the property in natural samples.
The team cleaved off single crystalline sheets 0.7 millimetres wide and applied the standard test for a topological insulator: photoelectron spectroscopy. This involves measuring the properties of electrons dislodged when ultraviolet light is fired at a material’s surface. Their results confirm that the electrons’ energy and momentum distribution matches predictions for a topological insulator.
Feng Liu, a materials scientist at the University of Utah in Salt Lake City, notes that the team’s natural sample contains fewer structural defects than its lab-made counterparts, reducing unwanted conduction in the bulk. “It may turn out to be cheaper to use a natural supply of topological insulators,” says Liu.
Obviously, these material are not in such high demand right now. But wait till something useful can be made out of these things.