Regensburg 2016 – scientific programme

Parts | Days | Selection | Search | Updates | Downloads | Help

DS: Fachverband Dünne Schichten

DS 57: Topological Insulators II
(Joint session of DS and HL, organized by HL)

DS 57.8: 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 Pb_1−xSn_xSe(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).