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O: Fachverband Oberflächenphysik

O 21: Electronic Structure and Spin-Orbit Interaction I

O 21.6: Vortrag

Montag, 11. März 2013, 17:15–17:30, H42

Spin polarization of (001) surface states of the topological crystalline insulator Pb_1−xSn_xSe — •Bastian M. Wojek¹, Ryszard Buczko², Piotr Dziawa², Bogdan J. Kowalski², Magnus H. Berntsen¹, Balasubramanian Thiagarajan³, Andrzej Szczerbakow², Perła Kacman², Tomasz Story², and Oscar Tjernberg¹ — ¹KTH Royal Institute of Technology, Stockholm, Sweden — ²Institute of Physics, Polish Academy of Sciences, Warsaw, Poland — ³MAX IV Laboratory, Lund University, Lund, Sweden

It has recently been discovered, that the narrow-gap IV-VI semiconductor Pb_1−xSn_xSe undergoes a transition from a normal insulator into a topological-crystalline-insulating (TCI) state when the band structure is inverted at large enough Sn content and low temperatures [P. Dziawa et al., Nat. Mater. 11, 1023–1027 (2012)]. In the TCI phase, the mirror symmetry of the crystal warrants the topological protection of metallic surface states in this material [T. H. Hsieh et al., Nat. Commun. 3, 982 (2012)].

Here, we study the (001) surface states of Pb_1−xSn_xSe. Our calculations not only predict metallic surface states with a chiral spin structure for the TCI state but also gapped surface states with nonzero polarization when the system is a normal insulator. For both phases, angle- and spin-resolved photoemission experiments provide conclusive evidence for the formation of these surface states and their chiral spin structure.