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Issue 20, 2017
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Granular topological insulators

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We demonstrate experimentally that a macroscopic topological insulator (TI) phase can emerge in a granular conductor composed of an assembly of tunnel coupled TI nanocrystals of dimension ∼10 nm × 10 nm × 2 nm. Electrical transport measurements on thin films of Bi2Se3 nanocrystals reveal the presence of decoupled top and bottom topological surface states that exhibit large surface state penetration depths (∼30 nm at 2 K). By tuning the size of the nanocrystals and the couplings between them, this new class of TIs may be readily tuned from a non-topological to a topological insulator phase, that too with designer properties. Paradoxically, this seemingly ‘dirty’ system displays properties that are closer to an ideal TI than most known single crystal systems, making granular/nanocrystalline TIs an attractive platform for future TI research.

Graphical abstract: Granular topological insulators

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The article was received on 23 Feb 2017, accepted on 23 Apr 2017 and first published on 28 Apr 2017

Article type: Paper
DOI: 10.1039/C7NR01355H
Citation: Nanoscale, 2017,9, 6755-6764
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    Granular topological insulators

    A. Banerjee, O. Deb, K. Majhi, R. Ganesan, D. Sen and P. S. Anil Kumar, Nanoscale, 2017, 9, 6755
    DOI: 10.1039/C7NR01355H

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