Dresden 2017 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 70: Topological Insulators I (joined session with TT)
HL 70.9: Vortrag
Donnerstag, 23. März 2017, 12:15–12:30, POT 251
Quantum Hall effect in three-dimensional Bi2Se3 single crystals — •Olivio Chiatti1, Marco Busch1, Sergio Pezzini2, Steffen Wiedmann2, Oliver Rader3, Lada V. Yashina4, and Saskia F. Fischer1 — 1Novel Materials Group, Humboldt-Universität zu Berlin, 12489 Berlin, Germany — 2High Field Magnet Laboratory, Radboud University Nijmegen, 6525ED Nijmegen, The Netherlands — 3Helmholtz-Zentrum-Berlin für Materialien und Energie, 12489 Berlin, Germany — 4Department of Chemistry, Moscow State University, 119991 Moscow, Russia
Topological insulators present surface (or edge) states of helically spin-polarized Dirac fermions, which are readily identified by spectroscopic methods. However, they are not so easily identified in transport, because they can be masked by bulk states. Bi2Se3 is one of the prototype topological insulators, but investigating transport by surface states has been hampered by residual bulk charge carriers. We have investigated nominally undoped, high-quality Bi2Se3 single crystals, with bulk electron densities of n ≈ 1.8·1019 cm−3 and mobilities of up to µ ≈ 103 cm2/Vs. Surface states have been confirmed by ARPES measurements [1]. We have measured magnetotransport between T = 0.3 K and T = 72 K, for tilted magnetic fields up to B = 33 T. We observe both Shubnikov-de Haas (SdH) effect and quantum Hall effect (QHE). The SdH oscillations appear dominated by 3D bulk charge carriers. However, the scaling of the QHE with sample thickness can be interpreted as transport over layered 2D states in the bulk.
[1] Chiatti et al., Sci. Rep. 6, 27483 (2016)