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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, it was shown that metal hydrides exhibit strong electron correlations in a single $3d-x^2-y^2}$ band at the Fermi level, similar to the cuprates but at room temperature.
Abstract: To achieve room-temperature superconductivity, a mechanism is needed that provides heavy quasiparticles at room temperature. In heavy fermion systems such localization is prototypically present only at liquid helium temperatures. In these $f$-electron Kondo systems, conduction electrons magnetically couple to localized moments, enhancing their mass and scatting time. These quasiparticles may form Cooper pairs and cause unconventional superconductivity with a critical temperature $T_c$ of the order of the Fermi energy $\varepsilon_F$. In relative terms, this $T_c$ is much larger than in cuprate or BCS superconductors for which $T_c\ll \varepsilon_F$. This suggests that Kondo systems in general have the potential to be high-temperature superconductors. For this to occur, strong correlations that cause electron localization need to take place at much larger temperatures. Here we show that metal hydrides manifest strong electron correlations in a single $3d_{x^2-y^2}$ band at the Fermi level, similar to the cuprates but at room temperature. Hole doping of this band, by varying the hydrogen content, causes divergence of the carrier mass and suggests the approach of an ordered Mott transition with signatures of a correlated metallic Kondo lattice. These room-temperature phenomena are expected to be widespread across hydrogen-rich compounds, and offer a promising novel ground to encounter unconventional superconductivity in the class of the metallic hydrides.
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TL;DR: In this article, the properties of the density-mobility dependence in such Mott-Hubbard unstable systems in general form were investigated and it was shown that it reveals some common general features important for considerations of transport properties.
Abstract: Coupling with large quasi momenta and presence of carriers of different signs of the effective mass, which are the main features of the high- T c superconductivity mechanism developed recently by Kopaev et al., have found the experimental evidence in our previous works. It has been shown that dc resistivity and Hall effect temperature behaviour can be explained by the model of the paraelectric close to the point of the Mott–Hubbard instability. This model possesses the above-mentioned characteristic features. Here we consider in more details the properties of the density–mobility dependence in such Mott–Hubbard unstable systems in general form and show that it reveals some common general features important for considerations of transport properties.
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TL;DR: In this article, a four-lattice-constant range hopping and the on-site Hubbard interaction were introduced to the Kane-Mele model and the critical strength of the long-range hopping $t_L$ at which the topological transition occurs in the non-interacting limit of the model was obtained.
Abstract: The interacting Kane-Mele model with a long-range hopping is studied using analytical method. The original Kane-Mele model is defined on a honeycomb lattice. In the work, we introduce a four-lattice-constant range hopping and the on-site Hubbard interaction into the model and keep its lattice structure unchanged. From the single-particle energy spectrum, we obtain the critical strength of the long-range hopping $t_L$ at which the topological transition occurs in the non-interacting limit of the model and our results show that it is independent of the spin-orbit coupling. After introducing the Hubbard interaction, we investigate the Mott transition and the magnetic transition of the generalized strongly correlated Kane-Mele model using the slave-rotor mean field theory and Hartree-Fock mean field theory respectively. In the small long-range hopping region, it is a correlated quantum spin Hall state below the Mott transition, while a topological Mott insulator above the Mott transition. By comparing the energy band of spin degree of freedom with the one of electrons in non-interacting limit, we find a condition for the $t_L$-driven topological transition. Under the condition, critical values of $t_L$ at which the topological transition occurs are obtain numerically from seven self-consistency equations in both regions below and above the Mott transition. Influences of the interaction and the spin-orbit coupling on the topological transition are discussed in this work. Finally, we show complete phase diagrams of the generalized interacting topological model at some strength of spin-orbital coupling.
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01 Jan 1988TL;DR: In this article, the authors review what they have learned from these calculations regarding the electronic structure of the family of high T/sub c/ materials and find out how relevant the LSD/LDA is for the electronic properties of cupric oxides.
Abstract: The discovery of high T/sub c/ superconductivity in cupric oxides has led, amongst other things, to numerous electronic bandstructure studies of these compounds. The foundation of these calculations is Density Functional Theory (DFT) and they are implemented with the Local Density Approximation (LDA) or Local Spin Density (LSD) approximation. In this article we will review what we have learned from these calculations regarding the electronic structure of the family of high T/sub c/ materials. To answer this we have to find out how relevant the LSD/LDA is for the electronic properties of cupric oxides. It is well known that the application of LDA DFT for transition metal oxides is fraught with difficulty and controversy. Although the LDA describes the variation of the equilibrium volume through the 3d transition metal oxides, including the volume expansion associated with Mott insulators, the theory fails to describe FeO and CoO as antiferromagnetic insulators, and in the case of NiO and MnO where the LDA does yield an insulating ground state, the band gap is grossly underestimated. Evidently the high-T/sub c/ materials are systems that are on the verge of undergoing a Mott transition; consequently, it is necessary to be circumspect regarding the applicability of LDA DFT both in the metallic (superconducting) and magnetic insulating states. 23 refs., 12 figs.