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TT: Fachverband Tiefe Temperaturen
TT 84: Topological Insulators II
(Joint session of DS, HL, MA, O and TT organized by O)
TT 84.8: Talk
Friday, March 11, 2016, 11:45–12:00, H15
Observation of gapped surface states in the topological regime of the quantum-phase transition in Bi-doped Pb-Sn-Se (111) epitaxial films — •Partha Sarathi Mandal1, Gunther Springholz2, Valentyn Volobuev2, Günther Bauer2, Evangelos Golias1, Andrei Varykhalov1, Jaime Sa’nchez-Barriga1, and Oliver Rader1 — 1Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany — 2Institut für Halbleiter und Festkörperphysik, Johannes Kepler Universität, Linz, Austria
Topological crystalline insulators are believed to show a straight forward and versatile connection between mirror symmetries and gap opening at the surface Dirac points. Here we systematically studied the trivial-to-topological insulator phase transition [1] of the Pb1−xSnxSe(111) surface grown by molecular beam epitaxy and using angle-resolved photoemission spectorscopy (ARPES) under variation of Sn concentration (10 to 28% ) and temperature. Differently from the case of the (001) surface [2], we observe two types of Dirac cones centered at Γ and M in the surface Brillouin zone. By comparing the band structure of samples with fixed Sn concentration and different Bi doping, we demonstrate the existence of gapped surface states within the topological regime of the quantum-phase transition at low temperatures [1].
[1] Y. Ando and L. Fu Annual Review of Condensed Matter Physics Vol. 6: 361-381 (2015). [2] Y. Tanaka, T. Shoman, K. Nakayama, S. Souma, T. Sato, T. Takahashi, M. Novak, Kouji Segawa, and Yoichi Ando PHYSICAL REVIEW B 88, 235126 (2013).