Kawazulite – A natural topological insulator

Topological insulators represent a new state of matter that is topologically distinct from conventional band insulators. The interlocking of spin and momentum in their surface states opens up promising perspectives for applications in spintronics. Using angle-resolved photoemission spectroscopy and magnetotransport experiments, we demonstrate that Kawazulite, a mineral occurring in gold mines, is a natural topological insulator. Owing to its relatively low bulk doping level and good carrier mobility, Kawazulite readily competes with its synthetic counterparts.