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arXiv · 1311.6637

A Natural Topological Insulator

Pascal Gehring·Hadj M. Benia·Ye Weng·Robert Dinnebier·Christian R. Ast·Marko Burghard·Klaus Kern
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Abstract

The earth's crust and outer space are rich sources of technologically relevant materials which have found application in a wide range of fields. Well-established examples are diamond, one of the hardest known materials, or graphite as a suitable precursor of graphene. The ongoing drive to discover novel materials useful for (opto)electronic applications has recently drawn strong attention to topological insulators. Here, we report that Kawazulite, a mineral with the approximate composition Bi$_2$(Te,Se)$_2$(Se,S), represents a naturally occurring topological insulator whose electronic properties compete well with those of its synthetic counterparts. Kawazulite flakes with a thickness of a few tens of nanometers were prepared by mechanical exfoliation. They exhibit a low intrinsic bulk doping level and correspondingly a sizable mobility of surface state carriers of more than $1000 \text{cm}^2/(\text{V s})$ at low temperature. Based on these findings, further minerals which due to their minimized defect densities display even better electronic characteristics may be identified in the future.

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Pascal Gehring, Hadj M. Benia, Ye Weng, Robert Dinnebier, Christian R. Ast, Marko Burghard, Klaus Kern. 2013-11-26. A Natural Topological Insulator. https://doi.org/10.1021/nl304583m

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