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New insights into band inversion and topological phase of TiNI monolayer.
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In this article , the authors show that the TiNI monolayer has a trivial bandgap in the equilibrium state with no band inversion, despite spin-orbit coupling (SOC) opening the band gap.Abstract:
Two-dimensional (2D) topological insulators (TIs) hold great promise for future quantum information technologies. Among the 2D-TIs, the TiNI monolayer has recently been proposed as an ideal material for achieving the quantum spin Hall effect at room temperature. Theoretical predictions suggest a sizable bandgap due to the spin-orbit coupling (SOC) of the electrons at and near the Fermi level with a nontrivial 2 topology of the electronic states, which is robust under external strain. However, our detailed first-principles calculations reveal that, in contrast to these predictions, the TiNI monolayer has a trivial bandgap in the equilibrium state with no band inversion, despite SOC opening the bandgap. Moreover, we show that electron correlation effects significantly impact the topological and structural stabilities of the system under external strains. We employed a range of density functional theory (DFT) approaches, including HSE06, PBE0, TB-mBJ, and GGA+U, to comprehensively investigate the nontrivial topological properties of this monolayer. Our results demonstrate that using general-purpose functionals such as PBE-GGA for studying TIs can lead to false predictions, potentially misleading experimentalists in their efforts to discover new TIs.read more
Citations
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Ab-initio overestimation of the topological region in Eu-based compounds
TL;DR: In this paper , Santos-Cottin et al. revisited first-principle results obtained earlier for EuCd2As2 and extended the computational studies to the whole class of systems EuIn2X2 (X = P, As, Sb, Bi), to nonmagnetic AEIn 2As2 (AE= Ca, Sr, Ba) employing a hybrid functional method.
References
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Generalized Gradient Approximation Made Simple
TL;DR: A simple derivation of a simple GGA is presented, in which all parameters (other than those in LSD) are fundamental constants, and only general features of the detailed construction underlying the Perdew-Wang 1991 (PW91) GGA are invoked.
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Colloquium: Topological insulators
M. Z. Hasan,Charles L. Kane +1 more
TL;DR: In this paper, the theoretical foundation for topological insulators and superconductors is reviewed and recent experiments are described in which the signatures of topologically insulators have been observed.
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Hybrid functionals based on a screened Coulomb potential
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Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
TL;DR: In this article, the quantum spin Hall (QSH) effect can be realized in mercury-cadmium telluride semiconductor quantum wells, a state of matter with topological properties distinct from those of conventional insulators.