Mott transition

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

Van Hove singularities in the paramagnetic phase of the Hubbard model: DMFT study

Abstract: Using the dynamical mean-field theory (DMFT) with the numerical renormalization-group impurity solver we study the paramagnetic phase of the Hubbard model with the density of states (DOS) corresponding to the three-dimensional (3D) cubic lattice and the two-dimensional (2D) square lattice, as well as a DOS with inverse square-root singularity. We show that the electron correlations rapidly smooth out the square-root van Hove singularities (kinks) in the spectral function for the 3D lattice and that the Mott metal-insulator transition (MIT) as well as the magnetic-field-induced MIT differ only little from the well-known results for the Bethe lattice. The consequences of the logarithmic singularity in the DOS for the 2D lattice are more dramatic. At half filling, the divergence pinned at the Fermi level is not washed out, only its integrated weight decreases as the interaction is increased. While the Mott transition is still of the usual kind, the magnetic-field-induced MIT falls into a different universality class as there is no field-induced localization of quasiparticles. In the case of a power-law singularity in the DOS at the Fermi level, the power-law singularity persists in the presence of interaction, albeit with a different exponent, and the effective impurity model in the DMFT turns out to be a pseudogap Anderson impurity model with a hybridization function which vanishes at the Fermi level. The system is then a generalized Fermi liquid. At finite doping, regular Fermi-liquid behavior is recovered.

Spin dynamics at the Mott transition and in the metallic state of the Cs3C60 superconducting phases

Abstract: We present here 13C and 133Cs NMR spin lattice relaxation T1 data in the A15 and fcc-Cs3C60 phases for increasing hydrostatic pressure through the transition at pc from a Mott insulator to a superconductor. We evidence that for ppc the (T1T)− 1 data above Tc display metallic-like Korringa constant values which match quantitatively previous data taken on other A3C60 compounds. However below the pressure for which Tc goes through a maximum, (T1T)− 1 is markedly increased with respect to the Korringa values expected in a simple BCS scenario. This points out the importance of electronic correlations near the Mott transition. For ppc singular T-dependences of (T1T)− 1 are detected for TTc. It will be shown that they can be ascribed to a large variation with temperature of the Mott transition pressure pc towards a liquid-gas-like critical point, as found at high T for usual Mott transitions.

Purely electronic terahertz polarization in dimer Mott insulators

Abstract: We theoretically describe purely electronic polarization modes in terahertz frequency region in dimer Mott insulators $\ensuremath{\kappa}\text{\ensuremath{-}}{(\text{BEDT-TTF})}_{2}\text{X}$. The unusual low-frequency modes arise from the coupling between the oscillation of intradimer electric dipole moments and that of alternating interdimer bond orders. These collective modes play an important role in the dynamical dielectric properties of the dimer Mott insulators. Near the phase boundary of the dimer Mott transition, the ferroelectric ground state is realized by introducing electron-lattice coupling as a result of the softening of one of these collective modes.