Berlin 2015 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 92: Topological Insulators I (jointly with MA, DS, HL, O)

TT 92.5: Talk

Thursday, March 19, 2015, 10:30–10:45, EB 202

Atomic relaxations in Bi₂Se₃ (0001) — Sumalay Roy¹, •Holger L. Meyerheim¹, Katayoon Mohseni¹, Arthur Ernst¹, Mikhail Otrokov^2,3, Maia G. Vergniory^1,2, Gregor Mussler⁴, Christian Tusche¹, Evgueni Chulkov^2,3, and Jürgen Kirschner^1,5 — ¹MPI f. Mikrostrukturphysik, D-06120 Halle, Germany — ²DIPC, San Sebastian, Spain — ³Tomsk St. Univ. , Russia — ⁴FZ Jülich, Germany — ⁵MLU Halle-Wittenberg, Germany

Surface x-ray diffraction analysis of the Bi₂Se₃(0001) surface reveals an expansion of the top Se-Bi interlayer spacing in the range between 2 and 17% relative to the bulk. It is directly related to the concentration of surface contaminants like carbon and is observed in both, single crystals and MBE grown ultrathin films. Deeper layers and the first van der Waals gap remain unrelaxed. Ab-initio calculations which are in agreement with angular resolved photoemission experiments reveal that carbon acts as an n-dopant, while the top layer expansion induces a shift of the Dirac point towards the bulk conduction band of Bi₂Se₃ [1,2].

[1] S. Roy, H.L. Meyerheim, A. Ernst et al., PRL 113, 116802 (2014);

[2] S. Roy, H.L. Meyerheim, K. Mohseni et al., PRB 90, 155456 (2014)

This work is supported by SPP1666 (Topological Insulators) of the DFG.