Dresden 2017 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 76: Poster Session: Transport 2
TT 76.8: Poster
Thursday, March 23, 2017, 15:00–19:00, P2-OG1
Strain Engineering of the Band Structure of HgTe Quantum Wells — •Lukas Lunczer, Philipp Leubner, Christoph Brüne, Hartmut Buhmann, and Laurens W. Molenkamp — Experimentelle Physik III, Physikalisches Institut, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
The HgTe quantum well (QW) is a well-characterized two-dimensional topological insulator (2D TI). Its band gap EG is relatively small (typically in the order of 10 meV), which restricts the observation of purely topological conductance to low temperatures.
Here, we utilize the strain dependence of the band structure of HgTe QWs to address this limitation. We use CdTe-Cd0.5Zn0.5Te strained-layer superlattices (SLS) on GaAs as virtual substrates with adjustable lattice constant to control the strain of the QW.
We present magnetotransport measurements, which demonstrate a transition from a semimetallic to a 2D-TI regime in wide QWs, when the strain is changed from tensile to compressive.
Most notable, we demonstrate a much enhanced energy gap of 55 meV in heavily compressively strained QWs. This value exceeds the highest possible gap on common II-VI substrates by a factor of 2-3, and extends the regime where topological conductance prevails to much higher temperatures.