Regensburg 2013 – scientific programme

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O: Fachverband Oberflächenphysik

O 38: Topological Insulators (jointly with HL, MA, TT)

O 38.7: Talk

Wednesday, March 13, 2013, 10:45–11:00, H16

Controllable magnetic doping of the surface state of a topological insulator — •A. Eich¹, T. Schlenk¹, M. Bianchi², M. Koleini³, O. Pietzsch¹, T.O. Wehling³, T. Frauenheim³, A. Balatsky⁴, J.-L. Mi⁵, B. B. Iversen⁵, J. Wiebe¹, A.A. Khajetoorians¹, Ph. Hofmann², and R. Wiesendanger¹ — ¹Institute for Applied Physics, Universität Hamburg, Germany — ²iNano, Aarhus University, Denmark — ³Bremen Center for Computational Materials Science, Universitiy of Bremen, Germany — ⁴NORDITA, Stockholm, Sweden — ⁵Center for Materials Crystallography, iNano, Aarhus University, Denmark

A combined experimental and theoretical study of doping individual Fe atoms into Bi₂Se₃ is presented. It is shown through a scanning tunneling microscopy study that single Fe atoms initially located at hollow sites on top of the surface (adatoms) can be incorporated into subsurface layers by thermally-activated diffusion. Angle-resolved photoemission spectroscopy in combination with ab-initio calculations within density functional theory suggest that the doping behavior changes from electron donation for the Fe adatom to neutral or electron acceptance for Fe incorporated into substitutional Bi sites. According to the calculations, these Fe substitutional impurities retain a large magnetic moment thus presenting an alternative scheme for magnetically doping the topological surface state. For both types of Fe doping, we see no indication of a gap at the Dirac point.
T. Schlenk et al., arXiv: 1211.2142v1 (2012) [cond-mat.mtrl-sci]
J. Honolka et al., PRL 108, 256811 (2012)