The effect of substrate and surface plasmons on symmetry breaking at the substrate interface of the topological insulator Bi 2 Te 3
Artikel i vetenskaplig tidskrift, 2019

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 Bi 2 Te 3 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 Bi 2 Te 3 and the substrate. We confirm the symmetry breaking in Bi 2 Te 3 via the emergence of the Raman-forbidden A1u2 mode. Our results suggest that topological surface states can exist at the Bi 2 Te 3 /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.

Författare

M. Wiesner

Uniwersytet im. Adama Mickiewicza w Poznaniu

The University of Texas at Austin

Richard H. Roberts

The University of Texas at Austin

Jung Fu Lin

The University of Texas at Austin

D. Akinwande

The University of Texas at Austin

Thorsten Hesjedal

University of Oxford

Liam B. Duffy

University of Oxford

Shu Min Wang

Chalmers, Mikroteknologi och nanovetenskap (MC2), Fotonik

Chinese Academy of Sciences

Y Song

Chinese Academy of Sciences

Jacek Jenczyk

Uniwersytet im. Adama Mickiewicza w Poznaniu

Stefan Jurga

Uniwersytet im. Adama Mickiewicza w Poznaniu

B. Mroz

Uniwersytet im. Adama Mickiewicza w Poznaniu

Scientific Reports

2045-2322 (ISSN)

Vol. 9 1 6147

Ämneskategorier

Materialkemi

Annan fysik

Den kondenserade materiens fysik

DOI

10.1038/s41598-019-42598-9

Mer information

Senast uppdaterat

2019-07-22