Berlin 2018 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 68: Topological Insulators and Weyl Semimetals (joint session MA/TT)
TT 68.1: Talk
Wednesday, March 14, 2018, 15:00–15:15, EB 407
Topological Phase Transitions from Relativistic Many-Body Calculations — •Irene Aguilera, Christoph Friedrich, and Stefan Blügel — Peter Grünberg Institute and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany.
We discuss topological phase transitions (TPTs) on the basis of relativistic GW and quasiparticle self-consistent GW (QSGW) calculations where the spin-orbit coupling is incorporated directly into the self-energy. TPTs can be caused by the variation of the thickness of a sample, the spin-orbit strength, alloying, strain, etc. The well known underestimation of band gaps in standard DFT translates into an overestimation of the inverted band gaps that are responsible for the topological character of materials. This results in standard DFT being unable to provide correctly the critical points of TPTs. As practical examples, we concentrate on semimetals Bi and Sb. In addition to the TPT that bismuth undergoes under strain [1], we discuss that a thickness-mediated TPT can also occur. This sheds light on the discrepancies about the topological or trivial character of bulk-like samples of Bi. Finally, we simulate Bi1−xSbx alloys varying the Sb concentration in order to find the critical concentration for which the system becomes a topological insulator.
[1] I. Aguilera et al., Phys. Rev. B 91, 125129 (2015).
Financial support from the Virtual Institute for Topological Insulators of the Helmholtz Association.