[institut] seminar sreda 10. maj

[Rados Gajic]

Postovane Koleginice i Kolege,
Professor Udo Schwingenschloegel
ce biti nas gost sledece nedelje
i odrzace predavanje

u sredu, 10. maj, biblioteka, 13:00

Pozdravi svima, Rados.

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Udo Schwingenschloegl

King Abdullah University of Science and Technology (KAUST), Physical
Sciences and Engineering (PSE), Thuwal 23955-6900, Saudi Arabia

Designing topological states by pressure, strain, and functionalization

Phase transitions in TlBiS2 and TlSbS2 are identified by parity
analysis and by calculating the surface states. Zero, one, and four
Dirac cones are found for the (111) surfaces of both TlBiS2 and TlSbS2
when the pressure grows, which confirms trivial-nontrivial-trivial
phase transitions. The Dirac cones at the M points are anisotropic
with large out-of-plane component. TlBiS2 shows normal, topological,
and topological crystalline insulator phases under hydrostatic
pressure, thus being the first compound to exhibit a phase transition
from a topological to a topological crystalline insulator. While
monolayer arsenic and arsenic antimonide are semiconductors (direct
band gap at the G point), fluorination results for both compounds in
Dirac cones at the K points. Fluorinated monolayer arsenic shows a
band gap of 0.16 eV due to spin-orbit coupling and fluorinated arsenic
antimonide a larger band gap of 0.37 eV due to inversion symmetry
breaking. Spin-orbit coupling induces spin splitting similar to
monolayer MoS2. Phonon calculations confirm that both materials are
dynamically stable. Calculations of the edge states of nanoribbons by
the tight-binding method demonstrate that fluorinated arsenic is
topologically nontrivial in contrast to fluorinated arsenic

Journal References:
- Sci. Rep. 5, 8379 (2015)
- Phys. Rev. B 93, 045312 (2016)
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