Regensburg 2019 – scientific programme

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O: Fachverband Oberflächenphysik

O 62: Poster Wednesday: Topology and Symmetry-Protected Materials

O 62.8: Poster

Wednesday, April 3, 2019, 17:45–20:00, Poster B1

Anomalous behavior of the electronic structure of (Bi_1−xIn_x)₂Se₃ across the quantum-phase transition from topological to trivial insulator — •Friedrich Freyse¹, Irene Aguilera², Lada Yashina³, Daria Tsukanova³, Alexander Chaika⁴, Carolien Callaert⁵, Artem Abakumov⁶, Joke Hadermann⁵, Andrei Varykhalov¹, Emile Rienks¹, Gustav Bihlmayer², Stefan Blügel², Oliver Rader¹, and Jaime Sánchez-Barriga¹ — ¹Helmholtz-Zentrum Berlin — ²Forschungszentrum Jülich and JARA — ³Moscow State University — ⁴Institute of Solid State Physics RAS — ⁵University of Antwerp — ⁶Skolkovo Institute of Science and Technology

Using spin- and angle-resolved photoemission and relativistic many-body calculations, we investigate the electronic structure of topological surface states (TSSs) across a topological quantum-phase transition in (Bi_1−xIn_x)₂Se₃ bulk single crystals. By increasing x, we observe how a surface gap opens at the Dirac point of the initially gapless TSS of Bi₂Se₃, leading to the existence of massive fermions with non-zero spin polarization. The surface gap monotonically increases for a wide range of x values in both the topological and trivial sides of the phase transition. Our calculations reveal qualitative agreement with the experimental results all across the quantum-phase transition upon the systematic variation of the spin-orbit coupling strength. A non-time-reversal symmetry-breaking mechanism of bulk-mediated scattering processes that increase with decreasing spin-orbit coupling strength is proposed as explanation.