Topological surface states in thick partially relaxed HgTe film

Abstract

Surface states of topological insulators (TIs) have been playing the central role in the majority of outstanding investigations in low-dimensional electron systems for more than 10 years. TIs based on high-quality strained HgTe films demonstrate a variety of subtle physical effects. The strain leads to a bulk band gap but limits a maximum HgTe strained film thickness, and therefore, the majority of experiments were performed on films with a thickness of less than 100 nm. Since a spatial separation of topological states is crucial for the study of a single-surface response, it is essential to increase the HgTe thickness further. In this work, by combining transport measurements together with capacitance spectroscopy, we perform an analysis of a 200-nm partially relaxed HgTe film. The Drude fit of the classical magnetotransport reveals the ambipolar electron-hole transport with a high electron mobility. A detailed analysis of Shubnikov-de Haas oscillations in both conductivity and capacitance allows us to distinguish three groups of electrons, identified as electrons on top and bottom surfaces and bulk electrons. The indirect bulk energy gap value is found to be close to zero. It is established that the significant gap decrease does not affect the surface states, which are found to be well resolved and spin nondegenerate. The presented techniques allow investigations of other three-dimensional TIs, regardless of the presence of bulk conductivity.

7 pages, 4 figures

References in corpus (12)

• Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class with spin-polarized single-Dirac-cone on the surface
• Topological quantum chemistry
• Topological superconductors: a review
• Gate-Voltage Control of Chemical Potential and Weak Anti-localization in Bismuth Selenide
• Observation of topological surface state quantum Hall effect in an intrinsic three-dimensional topological insulator
• Quantum Hall Effect on Top and Bottom Surface States of Topological Insulator (Bi1-xSbx)2Te3 Films
• Transport Properties of Topological Insulators: Band Bending, Bulk Metal-to-Insulator Transition, and Weak Anti-Localization
• Probing Spin Helical Surface States in Topological HgTe Nanowires
• Observation of Volkov-Pankratov states in topological HgTe heterojunctions using high-frequency compressibility
• Ballistic geometric resistance resonances in a single surface of a topological insulator
• Transport spectroscopy of induced superconductivity in the three-dimensional topological insulator HgTe
• Interaction between counter-propagating quantum Hall edge channels in the 3D topological insulator BiSbTeSe${}_2$

Cited by in corpus (6)

• Terahertz Magnetospectroscopy of Cyclotron Resonances from Topological Surface States in Thick Films of Cd${}_x$Hg${}_{1-x}$Te
• Spin and charge transport through helical Aharonov-Bohm interferometer with strong magnetic impurity
• Cyclotron resonance induced photogalvanic effect in surface states of 200 nm thick strained HgTe films
• Transport properties of a 1000-nm HgTe film: the interplay of surface and bulk carriers
• Scattering anisotropy in HgTe (013) quantum well
• Weak antilocalization in partially relaxed 200-nm HgTe films