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Mott transition

About: Mott transition is a research topic. Over the lifetime, 2444 publications have been published within this topic receiving 78401 citations.


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TL;DR: In this article , a density functional theory (DFT)-based analysis revealed that the intermediate phase in the PT, the so-called monoclinic metal phase, is a zero indirect band gap semimetal with a pseudo gap (199 meV).
Abstract: The structural phase transition (SPT) and metal-insulator phase transition (MIT) always occur simultaneously upon heating from the low-temperature insulator M1 phase to the high-temperature metal R phase in vanadium dioxide, and it is still unclear which one of Mott correlation and Peierls distortion plays a decisive role in the thermally induced phase transition (PT) since 1959. Our density functional theory (DFT)-based calculations revealed that the intermediate phase in the PT, the so-called monoclinic metal phase, is a zero indirect band gap semimetal (P21/c space group) with a pseudo gap (199 meV). From the M1 phase to the monoclinic metal phase, the band gap decreases gradually to zero, and the bonding lengths between vanadium-vanadium atoms remain nearly constant. The SPT and MIT from the intermediate structure to the R phase occur simultaneously with a sudden change of bonding lengths between vanadium-vanadium atoms, in which electrons can jump down rather than jump up to the conduction band minimum (CBM) from the valence band maximum (VBM) under thermal fluctuation in order to lower the total energy of the system to push forward the occurrence of PT. The electron jumping does not require additional energy from Coulomb repulsion between electrons even though it is always present. This SPT is a typical Peierls PT or a pseudo Mott PT rather than an actual Mott PT in the each of the two stages. Our conclusions provide a new understanding of SPT and MIT in vanadium dioxide that has been debated for more than 80 years.

2 citations

Journal ArticleDOI
TL;DR: In this article, Anderson localization for a class of one-particle Schr\"odinger operators with random Zeeman interactions was studied and it was shown rigorously that, for positive values of x below the percolation threshold, the spectrum of the one-electron Schr''odinger operator near the band edges is dense pure-point, and the corresponding eigenfunctions are exponentially localized.
Abstract: The phenomenon of Anderson localization is studied for a class of one-particle Schr\"odinger operators with random Zeeman interactions. These operators arise as follows: Static spins are placed randomly on the sites of a simple cubic lattice according to a site percolation process with density x and coupled to one another ferromagnetically. Scattering of an electron in a conduction band at these spins is described by a random Zeeman interaction term that originates from indirect exchange. It is shown rigorously that, for positive values of x below the percolation threshold, the spectrum of the one-electron Schr\"odinger operator near the band edges is dense pure-point, and the corresponding eigenfunctions are exponentially localized. Localization near the band edges persists in a weak external magnetic field, H, but disappears gradually, as H is increased. Our results lead us to predict the phenomenon of colossal (negative) magnetoresistance and the existence of a Mott transition, as H and/or x are increased. Our analysis is motivated directly by experimental results concerning the magnetic alloy Eu_x Ca_1-x B_6.

2 citations

Journal ArticleDOI
TL;DR: In this paper, the phonon system mainly contributes to the heat conduction in BaCo 1- x Ni x S 2, which has quasi two-dimensional electronic nature and exhibits the Mott transition with varying x, has been measured by using polycrystalline samples.
Abstract: Thermal Conductivity κ of BaCo 1- x Ni x S 2 , which has quasi two-dimensional electronic nature and exhibits the Mott transition with varying x , has been measured by using polycrystalline samples. From the detailed consideration of the observed x and temperature dependence of κ, it is found that the phonon system mainly contributes to the heat conduction. The κ- x curve exhibits a significant dip structure at the insulator-metal phase boundary, where strong phonon scattering by the electron system is expected.

2 citations

Journal ArticleDOI
TL;DR: In this paper, the transport properties of Mott magnetic semiconductors dominated by Coulomb correlations in a narrow band were studied, through the example of HgCr2Se4 belonging to this new class of materials.
Abstract: The authors present a study of the transport properties of Mott magnetic semiconductors dominated by Coulomb correlations in a narrow band, through the example of HgCr2Se4 belonging to this new class of materials. Specific properties such as a critical Mott concentration for metal-insulator transitions at T approximately 0 four times larger than predicted by the classical one-electron theories, and the existence of a continuous semiconductor-to-metal transition upon cooling, are observed experimentally, in agreement with the authors model.

2 citations

Journal ArticleDOI
TL;DR: In this article, it was shown that there may appear different novel states in correlated systems close to localized-itinerant crossover, especially favorable conditions for that are met in low-dimensional and in frustrated systems.
Abstract: Recent studies demonstrated that there may appear different novel states in correlated systems close to localized-itinerant crossover. Especially favourable conditions for that are met in low-dimensional and in frustrated systems. In this paper I discuss on concrete examples some of such novel states. In particular, for some spinels and triangular systems there appears a "partial Mott transition", in which first some finite clusters (dimers, trimes, tetramers, heptamers) go over to the itinerant regime, and the real bulk Mott transition occurs only later. Also some other specific possibilities in this crossover regime are shortly discussed, such as spin-Peierls-Peierls transition in TiOCl, spontaneous charge disproportionation in some cases, etc.

2 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202334
202271
202165
202064
201968
201871