WebBoth Ta 2 NiS 5 (D 2h17 -Cmcm; a = 3.415 (1), b = 12.146 (3), c = 15.097 (4)Å) and Ta 2 NiSe 5 (C 2h6 -C2/c; a = 3.496 (1), b = 12.829 (3), c = 15.641 (4)Å; β = 90.53 (1)°) crystallize as layered structures with four formula units per cell. WebApr 1, 2012 · We report temperature-dependent angle-resolved photoemission spectroscopy measurement of Ta 2 NiSe 5 which shows a semiconductor-semiconductor structural phase transition at around 330 K. Characteristically, flat band at the top of the valence band is observed, which is ascribed to the excitonic insulator effect.

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WebAug 1, 2009 · Ta 2 NiSe 5 (henceforth TNS) is a layered compound with 4 chemical formulae per unit cell, where each atomic species is arranged in chains running along the crystal a axis, lending it a... WebMar 2, 2024 · Open Access Band hybridization at the semimetal-semiconductor transition of Ta2 NiSe5 enabled by mirror-symmetry breaking Matthew D. Watson, Igor Marković, … lappeen huoltomestarit

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WebTa2NiSe5 is a semimetal with exciton insulator transition at ~330K. Excitonic insulators are novel material systems exhibiting correlated electronic phases. Condensation of excitons … TNSe is a layered material bound by van-der Waals forces. It consists of parallel Tantalum and Nickel chains and is thus referred to as a quasi-one-dimensional material (see Fig. 1)32. Experimentally, the high-temperature phase exhibits an orthorhombic structure, which is distorted to a monoclinic … See more In this section, we present a complete and systematic DFT study of both TNSe and TNS using standard and more accurate functionals. While we find that the fine electronic properties … See more The interpretation of an excitonic insulator as a phase consisting of an excitonic condensate entails that an increase of temperature above a critical value leads to the melting of the condensate and hence to a bandgap … See more While DFT calculations generally provide a good starting point for discussing material properties, they often lack quantitative agreement with experimental results. It is known that one … See more Having established the importance of the structural instability in the determination of the insulating groundstate of TNSe, in this section we discuss … See more WebJul 7, 2024 · The excitonic insulator (EI) phase is a state of matter that was first proposed more than 50 years ago (1–3).It was theorized that below a critical temperature (T c), weakly screened Coulomb interactions in small bandgap semiconductors and semimetals could lead to the formation of an exciton condensate in the ground state ().In the proposed … lappeen hierontakoulu