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The effect of substrate and surface plasmons on symmetry breaking at the substrate interface of the topological insulator Bi2Te3

Abstract:
A pressing challenge in engineering devices with topological insulators (TIs) is that electron transport is dominated by the bulk conductance, and so dissipationless surface states account for only a small fraction of the conductance. Enhancing the surface-to-volume ratio is a common method to enhance the relative contribution of such states. In thin films with reduced thickness, the confinement results in symmetry-breaking and is critical for the experimental observation of topologically protected surface states. We employ micro-Raman and tip-enhanced Raman spectroscopy to examine three different mechanisms of symmetry breaking in Bi2Te3 TI thin films: surface plasmon generation, charge transfer, and application of a periodic strain potential. These mechanisms are facilitated by semiconducting and insulating substrates that modify the electronic and mechanical conditions at the sample surface and alter the long-range interactions between Bi2Te3 and the substrate. We confirm the symmetry breaking in Bi2Te3 via the emergence of the Raman-forbidden ܣଵ௨ ଶ mode. Our results suggest that topological surface states can exist at the Bi2Te3/substrate interface, which is in a good agreement with previous theoretical results predicting the tunability of the vertical location of helical surface states in TI/substrate heterostructures.
Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1038/s41598-019-42598-9

Authors


More by this author
Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Sub department:
Condensed Matter Physics
Oxford college:
Christ Church
Role:
Author
ORCID:
0000-0001-7947-3692


Publisher:
Nature Research
Journal:
Scientific Reports More from this journal
Volume:
9
Article number:
6147
Publication date:
2019-04-16
Acceptance date:
2019-04-01
DOI:
EISSN:
2045-2322


Keywords:
Pubs id:
pubs:987341
UUID:
uuid:fb8f3bc6-6a3e-4650-9f1b-1a3bcb24e693
Local pid:
pubs:987341
Source identifiers:
987341
Deposit date:
2019-04-01

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