Regensburg 2013 – scientific programme

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O: Fachverband Oberflächenphysik

O 55: Electronic Structure and Spin-Orbit Interaction II

O 55.9: Talk

Wednesday, March 13, 2013, 18:00–18:15, H42

Origin of Rashba-splitting in the quantized subbands at the Bi₂Se₃ surface — •Hadj Mohamed Benia¹, Alexander Yaresko¹, Andreas P. Schnyder¹, Jürgen Henk², Chentiang Lin¹, Klaus Kern^1,3, and Christian R. Ast¹ — ¹Max-Planck-Institut für Festkörperforschung, 70569 Stuttgart, Germany — ²Institut für Physik -Theoretische Physik, Martin-Luther-Universität Halle-Wittenberg, D- 06099 Halle (Saale), Germany — ³Institut de Physique de la Matière Condensée, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland

We study the band structure of the Bi₂Se₃ topological insulator (111) surface using angle-resolved photoemission spectroscopy (ARPES). We examine the situation where two sets of quantized subbands exhibiting different Rashba spin-splitting are created via bending of the conduction (CB) and the valence (VB) bands at the surface. We show that the potential gradients at both 2DEGs are similar and therefore not responsible for the splitting discrepancy. On the other hand, first principles calculations show that the contribution of Bi 6p states to the VB is clearly smaller than to the CB. Therefore, and since Bi 6p states are characterized by a strong spin-orbit coupling (SOC), the spin-splitting discrepancy is traced back to a difference in the SOC strength.