Berlin 2015 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 32: Transport: Topological Insulators 2 (jointly with DS, HL, MA, O)
TT 32.2: Talk
Tuesday, March 17, 2015, 09:45–10:00, H 3005
Emergence of surface conductivity at low temperatures in FeSi — •Michael Wagner, Ralf Korntner, Andreas Bauer, and Christian Pfleiderer — Physik-Department, Technische Universität München, D-85748 Garching, Germany
We report a comprehensive study of the influence of the sample quality on the Hall-conductivity in the correlated semiconductor FeSi. For our study three high-quality Fe1+xSi single crystals with slightly different Fe concentrations x were grown by optical float zoning under ultra-high vacuum compatible conditions. While the magnetic properties vary sensitively for the samples studied, the transport properties display several key features that are independent of the Fe concentration. As our main result we find, that the Hall-conductivity of FeSi can be described in terms of a Drude-model. For low temperatures a second transport channel emerges besides bulk conductivity, which can be assigned unambiguously to the sample surface. Remarkably, the mobility of this surface conduction is extraordinarily high as compared to similar effects in conventional semiconductors, being quantitatively consistent with topological insulators such as Bi2Te3 where they are viewed as the signature of topologically protected transport channels.