Regensburg 2013 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 58: Poster Session III (Solid-liquid interfaces; Scanning probe and other methods; Electronic structure theory; Spin-orbit interaction)

O 58.25: Poster

Mittwoch, 13. März 2013, 18:15–21:45, Poster B1

Imaging the local transport field of a Bi2Se3 surface — •Sebastian Bauer, Alexander M. Bernhart, Mark R. Kaspers, Rolf Möller, and Christian A. Bobisch — Faculty of Physics, Center of Nanointegration Duisburg-Essen, University of Duisburg-Essen, 47048 Duisburg, Germany

Since the prediction of the unique properties of topological insulators in 2007 [1] those new material class has become one of the most studied materials in condensed matter physics. To study the lateral variation of the electrochemical potential we performed scanning tunneling potentiometry (STP) [2] on the surface of thin films of Bi2Se3 grown on a Si(111) substrate. The films were prepared according to Zhang et al. [3]. All experiments, the preparation as well as the analysis, were carried out in situ under UHV conditions. For the STP measurements two tips of a four probe scanning tunneling microscope (STM) are contacted to the surface to apply an electric field parallel to the surface. A third tip simultaneously maps the topography and the local electrochemical potential of the surface [4]. We present first STP results showing a spatial variation of the electrochemical potential of the Bi2Se3 surface. In addition, to the transport field the thermovoltage of the tunneling barrier is detected. The two signals can be disentangled by reversal of the lateral current, because that changes the sign of the transport field leaving the thermovoltage unchanged. [1] L. Fu, C. Kane, and J. Mele, Phys. Rev. Lett. 98, 106803 (2007)[2] P. Muralt, D. Pohl, Appl. Phys. Lett. 48, 514 (1986)[3] G. Zhang, et al., Appl. Phys. Lett. 95, 053114 (2009)[4] J. Homoth, et al., Nano Letters 9, 1588 (2009)