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Fragility of the Dirac Cone Splitting in Topological Crystalline Insulator Heterostructures

Polley, Craig M. LU ; Buczko, Ryszard; Forsman, Alexander; Dziawa, Piotr; Szczerbakow, Andrzej; Rechciński, Rafał; Kowalski, Bogdan J. LU ; Story, Tomasz; Trzyna, Małgorzata and Bianchi, Marco, et al. (2018) In ACS Nano 12(1). p.617-626
Abstract

The "double Dirac cone" 2D topological interface states found on the (001) faces of topological crystalline insulators such as Pb1-xSnxSe feature degeneracies located away from time reversal invariant momenta and are a manifestation of both mirror symmetry protection and valley interactions. Similar shifted degeneracies in 1D interface states have been highlighted as a potential basis for a topological transistor, but realizing such a device will require a detailed understanding of the intervalley physics involved. In addition, the operation of this or similar devices outside of ultrahigh vacuum will require encapsulation, and the consequences of this for the topological interface state must be understood. Here we... (More)

The "double Dirac cone" 2D topological interface states found on the (001) faces of topological crystalline insulators such as Pb1-xSnxSe feature degeneracies located away from time reversal invariant momenta and are a manifestation of both mirror symmetry protection and valley interactions. Similar shifted degeneracies in 1D interface states have been highlighted as a potential basis for a topological transistor, but realizing such a device will require a detailed understanding of the intervalley physics involved. In addition, the operation of this or similar devices outside of ultrahigh vacuum will require encapsulation, and the consequences of this for the topological interface state must be understood. Here we address both topics for the case of 2D surface states using angle-resolved photoemission spectroscopy. We examine bulk Pb1-xSnxSe(001) crystals overgrown with PbSe, realizing trivial/topological heterostructures. We demonstrate that the valley interaction that splits the two Dirac cones at each X̄ is extremely sensitive to atomic-scale details of the surface, exhibiting non-monotonic changes as PbSe deposition proceeds. This includes an apparent total collapse of the splitting for sub-monolayer coverage, eliminating the Lifshitz transition. For a large overlayer thickness we observe quantized PbSe states, possibly reflecting a symmetry confinement mechanism at the buried topological interface.

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publication status
published
subject
keywords
angle-resolved photoemission spectroscopy (ARPES), quantum confinement, topological crystalline insulator, topological heterostructure, valley splitting
in
ACS Nano
volume
12
issue
1
pages
10 pages
publisher
The American Chemical Society
external identifiers
  • scopus:85042198890
ISSN
1936-0851
DOI
10.1021/acsnano.7b07502
language
English
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yes
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ea105ce3-dd1d-434a-a262-83ebdf692118
date added to LUP
2018-03-07 09:52:10
date last changed
2018-05-29 12:29:17
@article{ea105ce3-dd1d-434a-a262-83ebdf692118,
  abstract     = {<p>The "double Dirac cone" 2D topological interface states found on the (001) faces of topological crystalline insulators such as Pb<sub>1-x</sub>Sn<sub>x</sub>Se feature degeneracies located away from time reversal invariant momenta and are a manifestation of both mirror symmetry protection and valley interactions. Similar shifted degeneracies in 1D interface states have been highlighted as a potential basis for a topological transistor, but realizing such a device will require a detailed understanding of the intervalley physics involved. In addition, the operation of this or similar devices outside of ultrahigh vacuum will require encapsulation, and the consequences of this for the topological interface state must be understood. Here we address both topics for the case of 2D surface states using angle-resolved photoemission spectroscopy. We examine bulk Pb<sub>1-x</sub>Sn<sub>x</sub>Se(001) crystals overgrown with PbSe, realizing trivial/topological heterostructures. We demonstrate that the valley interaction that splits the two Dirac cones at each X̄ is extremely sensitive to atomic-scale details of the surface, exhibiting non-monotonic changes as PbSe deposition proceeds. This includes an apparent total collapse of the splitting for sub-monolayer coverage, eliminating the Lifshitz transition. For a large overlayer thickness we observe quantized PbSe states, possibly reflecting a symmetry confinement mechanism at the buried topological interface.</p>},
  author       = {Polley, Craig M. and Buczko, Ryszard and Forsman, Alexander and Dziawa, Piotr and Szczerbakow, Andrzej and Rechciński, Rafał and Kowalski, Bogdan J. and Story, Tomasz and Trzyna, Małgorzata and Bianchi, Marco and Grubišić Čabo, Antonija and Hofmann, Philip and Tjernberg, Oscar and Balasubramanian, Thiagarajan},
  issn         = {1936-0851},
  keyword      = {angle-resolved photoemission spectroscopy (ARPES),quantum confinement,topological crystalline insulator,topological heterostructure,valley splitting},
  language     = {eng},
  month        = {01},
  number       = {1},
  pages        = {617--626},
  publisher    = {The American Chemical Society},
  series       = {ACS Nano},
  title        = {Fragility of the Dirac Cone Splitting in Topological Crystalline Insulator Heterostructures},
  url          = {http://dx.doi.org/10.1021/acsnano.7b07502},
  volume       = {12},
  year         = {2018},
}