Massive and Topological Surface States in Tensile-Strained HgTe

Abstract

Magneto-transport measurements on gated highmobility heterostructures containing a 60 nm layer of tensile-strained HgTe, a three-dimensional topological insulator, show well-developed Hall quantization from surface states both in the n-as well as in the ptype regime. While the n-type behavior is due to transport in the topological surface state of the material, we find from 8-orbital k•p calculations that the p-type transport results from massive Volkov− Pankratov states. Their formation prevents the Dirac point and thus the p-conducting topological surface state from being accessible in transport experiments. This interpretation is supported by low-field magneto-transport experiments demonstrating the coexistence of nconducting topological surface states and p-conducting Volkov−Pankratov states at the relevant gate voltages.

Electron–Hole Scattering Limited Transport of Dirac Fermions in a Topological Insulator

“…This feature results from the inverted band ordering of the Γ 6 and Γ 8 − bands and hybridization with the Γ 8 + band which is located between them. 15,18,22 Such hybridization-induced van Hove singularities commonly occur in topological materials (see e.g. ref 23).…”

“…The main reason is the direct access to two-dimensional Dirac states with high mobility. The peculiar band structure of HgTe offers the possibility to simultaneously populate topological surface states and hole-type trivial states. , This allows the observation of both n- and p-type dominated transport in the same sample by means of electrostatic gating.…”

Electron-hole scattering limited transport of Dirac fermions in a topological insulator

“…The peculiar band structure of HgTe offers the possibility to simultaneously populate topological surface states and holetype trivial states. 11,12 This allows to observe both n-and p-type dominated transport in the same sample by means of electrostatic gating.…”

“…This feature results from the inverted band ordering of the Γ 6 and Γ − 8 bands and hybridization with the Γ + 8 band which is located between them. 9,12,16 Such hybridization-induced van Hove singularities commonly occur in topological materials (see e. g. 17 ).…”

Fluctuations in Planar Magnetotransport Due to Tilted Dirac Cones in Topological Materials

“…The plot is typical of a high-quality tensile-strained HgTe 3DTI sample. The double peak behavior results from the interplay of the high-mobility n -conducting topological surface states and gate-field induced p -conducting massive Volkov–Pankratov surface states . Subsequently, the magnetotransport of the sample was investigated in a vector magnet by applying an in-plane magnetic field of 1 T, yielding the angular dependence of R xx and R xy .…”