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Title: Quartic dispersion, strong singularity, magnetic instability, and unique thermoelectric properties in two-dimensional hexagonal lattices of group-VA elements
Authors: Sevinçli, Haldun
Sevinçli, Haldun
Izmir Institute of Technology. Materials Science and Engineering
Keywords: Magnetic instability
Quartic dispersion
Van Hove singularity
Two-dimensional materials
Issue Date: Apr-2017
Publisher: American Chemical Society
Source: Sevinçli, H. (2017). Quartic dispersion, strong singularity, magnetic instability, and unique thermoelectric properties in two-dimensional hexagonal lattices of group-VA elements. Nano Letters, 17(4), 2589-2595. doi:10.1021/acs.nanolett.7b00366
Abstract: The critical points and the corresponding singularities in the density of states of crystals were first classified by Van Hove with respect to their dimensionality and energy-momentum dispersions. Here, different from saddle-point Van Hove singularities, the occurrence of a continuum of critical points, which give rise to strong singularities in two-dimensional elemental hexagonal lattices, is shown using a minimal tight-binding formalism. The model predicts quartic energy-momentum dispersions despite quadratic or linear ones, which is also the origin of the strong singularity. Starting with this model and using first-principles density functional theory calculations, a family of novel two-dimensional materials that actually display such singularities are identified and their extraordinary features are investigated. The strong singularity gives rise to ferromagnetic instability with an inverse-square-root temperature dependence and the quartic dispersion is responsible for a steplike transmission spectrum, which is a characteristic feature of one-dimensional systems. Because of the abrupt change in transmission at the band edge, these materials have temperature-independent thermopower and enhanced thermoelectric efficiencies. Nitrogene has exceptionally high thermoelectric efficiencies at temperatures down to 50 K, which could make low-temperature thermoelectric applications possible.
ISSN: 1530-6984
Appears in Collections:Materials Science and Engineering / Malzeme Bilimi ve Mühendisliği
PubMed İndeksli Yayınlar Koleksiyonu / PubMed Indexed Publications Collection
Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection

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