Experimental Observation of Topological Edge States at the Surface Step Edge of the Topological InsulatorZrTe5

Abstract

We report an atomic-scale characterization of ZrTe_{5} by using scanning tunneling microscopy. We observe a bulk band gap of ∼80 meV with topological edge states at the step edge and, thus, demonstrate that ZrTe_{5} is a two-dimensional topological insulator. We also find that an applied magnetic field induces an energetic splitting of the topological edge states, which can be attributed to a strong link between the topological edge states and bulk topology. The relatively large band gap makes ZrTe_{5} a potential candidate for future fundamental studies and device applications.

Bipolar Conduction as the Possible Origin of the Electronic Transition in Pentatellurides: Metallic vs Semiconducting Behavior

“…As will be shown below, the resistivity peak and the thermopower sign reversal at T p can be reproduced by our parameter-free transport calculations when taking into account the intrinsic band structure anisotropies at the valence band maximum and conduction band minimum. Our results also provide a simple physical explanation for the contradictory reports in the literature regarding the electronic structure of ZrTe 5 , i.e., semiconductor versus Dirac semimetal [12][13][14][15][16][17][18].…”

“…2 in terms of the different chemical compositions. The transport properties of the Flux sample should be regarded as the intrinsic, or very close to the intrinsic, behaviors of ZrTe 5 ; the observed semiconducting-like ρðTÞ is consistent with the firstprinciples band structure calculations [11], showing a finite gap near the Fermi energy, as also detected by the scanning tunneling microscopy measurement [17]. The positive SðTÞ in the whole temperature range indicates that the Fermi level is slightly below the top of the valence band.…”

“…More recently, these compounds have become of interest as topological materials whose low-energy electronic structure is controlled by spin-orbit interactions [11]. Nevertheless, it is currently under hot debate whether they are insulators or Dirac semimetals [6,[12][13][14][15][16][17][18].…”

Observation of Optical and Electrical In-Plane Anisotropy in High-Mobility Few-Layer ZrTe5

“…S4(b) shows the transfer curve of two devices fabricated on the same L-shaped strip with the flake thickness of 7.8nm. Note the fact that as a three dimensional Dirac semimetal, even the monolayer of ZrTe5 is predicted to have a small bandgap of 100meV 3 . So it is reasonable that the FET device only has gate modulation of around 30% at room temperature.…”

“…Since then great efforts have been made towards expanding the spectrum of topological materials and bringing many conceptual materials into reality. Transition metal pentatellurides such as ZrTe5 and HfTe5 have been widely studied in bulk form since early 1980's due to their anomalous resistivity peak and X-ray diffraction intensity peak at low temperature 3,4 , large thermoelectric power 5 , pressure-induced superconductivity 6,7 , absence of a structural phase transition corresponding to resistivity anomaly 8 , and chiral magnetic effect 9 . In recent years, ZrTe5 research has been revived because of its non-trivial topological properties.…”