A gap in a topological surface state

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Science  17 Jul 2015:
Vol. 349, Issue 6245, pp. 280-281
DOI: 10.1126/science.349.6245.280-c

Topological insulators (TIs) have, in theory, conducting surfaces and insulating bulks. In practice, TIs often have a considerable bulk conductance that masks the conduction from the topologically protected surface states. To make the surface state nonconducting—in other words, to open a gap in its dispersion—researchers usually resort to magnetic doping. Now, Weber et al. demonstrate that a topological surface state of the compound Bi4Se3 is naturally, although partially, gapped. To show this, the authors use a combination of photoemission measurements and calculations. The results may be more general within the subclass of TIs to which Bi4Se3 belongs.

Phys. Rev. Lett. 10.1103/PhysRevLett.114.256401 (2015).

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