Regensburg 2016 – scientific programme
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DS: Fachverband Dünne Schichten
DS 38: Topological Insulators
(Joint session of DS, HL, MA, O and TT, organized by MA)
DS 38.7: Talk
Wednesday, March 9, 2016, 16:45–17:00, H32
Accessing the transport limits of topological states — •Thomas Bathon1, Paolo Sessi1, Konstantin Kokh2, Oleg Tereshchenko2, and Matthias Bode1 — 1Physikalisches Institut, Experimentelle Physik II, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany — 2Novosibirsk State University, 630090 Novosibirsk, Russia
Topological insulators host on their surface spin-momentum locked Dirac states. Beyond their fundamental interest, these materials raised great expectations to create new functionalities in spintronics and magneto-electrics. Their success depends on our understanding of their response to Coulomb perturbations such as electric fields, which can be effectively used to gate their surface. These phenomena have so far been primarily explored by spatially averaging techniques.
Here, by using scanning tunneling microscopy and spectroscopy, we visualize the response of topological states to local charges and electric fields at the nanoscale. We demonstrate that, contrary to the general believe, local electric fields can not be effectively screened by topological states, but penetrate into the bulk indicating a behavior which is far from being metallic. The analysis of our data allows to detect the existence of a finite conductivity which, because of the local character of our measurements, can be safely quantified without being affected by sample inhomogeinities. Finally, we will show how, by taking advantage of this intrinsic limitation, a new approach to tune both charge and spin transport in this fascinating class of materials can be explored.