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Seminars & Lectures

* TITLE

Topology of SmB6 determined by dynamical mean field theory

* SPEAKERS

Name	Affiliation	E-mail
Patrik Thunstrom	Uppsala University

* HOST(Applicant)

Name	Affiliation	E-mail
Research Support Team		ra(at)apctp.org

* DATE / TIME

2020-06-25, 17:00

* PLACE

ZOOM Webinar

* ABSTRACT

Whether SmB6 is a topological insulator remains hotly debated. There is compelling experimental evidence that one set of surface states previously considered topological is simply two parabolic trivial bands [1], which would indicate that SmB6 is simply a band insulator. However, the same experiment also shows a second set of surface states interpreted as Umklap states, although no ordered surface reconstruction was detected. To piece together this puzzle we performed density functional theory plus dynamical mean field theory calculations both for the bulk and different surface terminations [2]. Our results are in excellent agreement with a large range of experiments, from the Sm 4f 5.5 intermediate valency to X-ray and photoemission spectra. By analysing the symmetry of the Pole Extended (PE) Hamiltonian [3], which fully captures the self-energy, we prove that SmB6 is a strongly correlated topological insulator, albeit not a Kondo insulator. The analysis is very robust since it does not depend on the details of the local Sm 4f self-energy, only that the non-correlated band structure is well described by DFT. The topological surface states are analyzed, and the conflicting interpretations of photoemission data are resolved. Finally, we prove that the PE Hamiltonian is topological equivalent to the “topological Hamiltonian” [4] for local self-energies, but non-equivalent for non-local self-energies [2], which explains the breakdown of the
topological Hamiltonian analysis for some systems.

[1] P. Hlawenka et al., Nature Communications, 9, 517 (2018)
[2] Patrik Thunström and Karsten Held, under revision in Phys. Rev. Letters
[3] Lei Wang, Hua Jiang, Xi Dai, and X. C. Xie, Phys. Rev. B 85, 235135 (2012)
[4] Zhong Wang and Shou-Cheng Zhang, Phys. Rev. X 2, 031008 (2012)

■ ZOOM Webinar
1) Click the following
https://zoom.us/j/95383452795?pwd=NnNZdnZveHR1VjBTaGhHYzdJVzRJQT09
2) Join the webinar with your email account and name

■ Contact information
1) Host: Prof. Igor Di Marco (igor.dimarco@apctp.org)
2) Office: Research Support Team (ra@apctp.org)

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