Quantum spin Hall effect in two-dimensional transition metal dichalcogenides
By Xiaofeng Qian, Junwei Liu, Liang Fu, Ju Li. Science, 2014
1,821 citations recorded by the source corpus.
Quantum spin Hall (QSH) effect materials feature edge states that are topologically protected from backscattering. However, the small band gap in materials that have been identified as QSH insulators limits applications. We use first-principles calculations to predict a class of large-gap QSH insulators in two-dimensional transition metal dichalcogenides with 1T′ structure, namely, 1T′-MX2 with M = (tungsten or molybdenum) and X = (tellurium, selenium, or sulfur). A structural distortion causes an intrinsic band inversion between chalcogenide-p and metal-d bands. Additionally, spin-orbit coupling opens a gap that is tunable by vertical electric field and strain. We propose a topological field effect transistor made of van der Waals heterostructures of 1T′-MX2 and two-dimensional dielectric layers that can be rapidly switched off by electric field through a topological phase transition instead of carrier depletion. First-principles calculations are used to predict an exotic effect in a particular structure of WTe2 and related materials. Predicting an exotic state of matter Much like graphene, twodimensional flakes of transition metal dichalcogenides have appealing electronic properties. Qian et al. now find that certain structures of these materials may also exhibit the so-called spin Hall effect. The spin Hall effect represents an exotic state of matter in which a 2D material conducts electricity along its edge in a way that drastically reduces dissipation. To show this, the researchers used first-principle calculations and found that the materials also feature a large band gap, which reduces undesirable conduction through the bulk. Their proposed device could be switched on and off quickly using an electric field. Science, this issue p. 1344
Subfields: Atomic and Molecular Physics, and Optics, Materials Chemistry
View Paper: https://www.semanticscholar.org/paper/207d225c40aba45a950e8e1c519a17dba7ae0567
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Citations in the corpus
- A library of atomically thin metal chalcogenides (2018, background): “The atomic structures of most 2D crystals can be classified into four types: (1) the trigonal prismatic 1 H phase; (2) the undistorted 1 T phase with the metal atom located at the centre of an octahedral unit; (3) the one-dimensional distorted 1 T phase (called the 1 T′ phase), in which pairs of met”
- Evidence for Topological Edge States in a Large Energy Gap near the Step Edges on the Surface of ZrTe 5 (2016, background): “ [1,2]. These exotic properties have been inducing fantastic reveries in electronic device applications. Although considerable theoretical efforts have predicted many 2D TI candidates in recent years [3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17], only a few systems, such as the quantum wells”