Transport Properties of a 3D Topological Insulator based on a Strained High-Mobility HgTe Film

We investigate the magnetotransport properties of strained 80 nm thick HgTe layers featuring a high mobility of μ~4×10⁵ cm²/V·s. By means of a top gate, the Fermi energy is tuned from the valence band through the Dirac-type surface states into the conduction band. Magnetotransport measurements allow us to disentangle the different contributions of conduction band electrons, holes, and Dirac electrons to the conductivity. The results are in line with previous claims that strained HgTe is a topological insulator with a bulk gap of ≈15 meV and gapless surface states.