Metal-insulator transition in the one-dimensional SUÑNÖ Hubbard model (original) (raw)
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Journal of Magnetism and Magnetic Materials, 1995
We investigate the metal-insulator transition of the one-dimensional SU(N) Hubbard model for repulsive interaction. Using the bosonization approach a Mott transition in the charge sector at half-filling (kF =π/N a0) is conjectured for N > 2. Expressions for the charge and spin velocities as well as for the Luttinger liquid parameters and some correlation functions are given. The theoretical predictions are compared with numerical results obtained with an improved zero-temperature quantum Monte Carlo approach. The method used is a generalized Green's function Monte Carlo scheme in which the stochastic time evolution is partially integrated out. Very accurate results for the gaps, velocities, and Luttinger liquid parameters as a function of the Coulomb interaction U are given for the cases N = 3 and N = 4. Our results strongly support the existence of a Mott-Hubbard transition at a non-zero value of the Coulomb interaction. We find Uc ∼ 2.2 for N = 3 and Uc ∼ 2.8 for N = 4.
We show that backflow correlations in the variational wave function for the Hubbard model greatly improve the previous results given by the Slater-Jastrow state, usually considered in this context. We provide evidence that, within this approach, it is possible to have a satisfactory connection with the strong-coupling regime. Moreover, we show that, for the Hubbard model on the lattice, backflow correlations are essentially short range, inducing an effective attraction between empty (holons) and doubly occupied sites (doublons). In the presence of frustration, we report the evidence that the metal to Mott-insulator transition is marked by a discontinuity of the double occupancy, together with a similar discontinuity of the kinetic term that does not change the number of holons and doublons, while the other kinetic terms are continuous across the transition. Finally, we show the estimation of the charge gap, obtained by particle-hole excitationsà la Feynman over the ground-state wave function.
We investigate the nature of the interaction-driven Mott-Hubbard transition of the half-filled t 1 − t 2 Hubbard model in one dimension, using a full-fledged variational Monte Carlo approach including a distance-dependent Jastrow factor and backflow correlations. We present data for the evolution of the magnetic properties across the Mott-Hubbard transition and on the commensurate to incommensurate transition in the insulating state. Analyzing renormalized excitation spectra, we find that the Fermi surface renormalizes to perfect nesting right at the Mott-Hubbard transition in the insulating state, with a first-order reorganization when crossing into the conducting state.
The metal–insulator transition in the paramagnetic Hubbard Model
Physica B: Condensed Matter, 2008
We study the Mott transition in the Hubbard Model within the dynamical mean field theory (DMFT) approach. The DMFT equations are solved using the density matrix renormalization group technique. The densities of states for the half-filled and heavily doped cases are shown. The full phase diagram is also presented.
Finite Doping Signatures of the Mott Transition in the Two-Dimensional Hubbard Model
Physical Review Letters, 2010
Experiments on layered materials call for a study of the influence of short-range spin correlations on the Mott transition. To this end, we solve the cluster dynamical mean-field equations for the Hubbard model on a plaquette with continuous-time quantum Monte Carlo. The normal state phase diagram as a function of temperature T , interaction strength U and filling n reveals that upon increasing n towards the insulator, there is a surface of first-order transition between two metals at non-zero doping. For T above the critical end line there is a maximum in scattering rate.
Europhysics Letters (EPL), 2000
The Mott-Hubbard transition is studied in the context of the two-dimensional Hubbard model. Analytical calculations show the existence of a critical value Uc of the potential strength which separates a paramagnetic metallic phase from a paramagnetic insulating phase. Calculations of the density of states and double occupancy show that the ground state in the insulating phase contains always a small fraction of empty and doubly occupied sites. The structure of the ground state is studied by considering the probability amplitude of intersite hopping. The results indicate that the ground state of the Mott insulator is characterized by a local antiferromagnetic order; the electrons keep some mobility, but this mobility must be compatible with the local ordering. The vanishing of some intersite probability amplitudes at U = Uc puts a constrain on the electron mobility. It is suggested that such quantities might be taken as the quantities which control the order in the insulating phase.
Filling-driven Mott transition in SU(N) Hubbard models
Physical Review B
We study the filling-driven Mott transition involving the metallic and paramagnetic insulating phases in SU(N) Fermi-Hubbard models, using dynamical mean-field theory (DMFT) and the numerical renormalization group (NRG) as impurity solver. The compressibility shows a striking temperature dependence: near the critical temperature, it is strongly enhanced in the metallic phase close to the insulating phase. We demonstrate that this compressibility enhancement is associated with the thermal suppression of the quasiparticle peak in the local spectral functions. We also explain that the asymmetric shape of the quasiparticle peak originates from the asymmetry in the underlying doublon-holon dynamics.
Physical Review B, 2007
In this paper we present a determinant quantum monte carlo study of the two dimensional Hubbard model with random site disorder. We show that, as in the case of bond disorder, the system undergoes a transition from an Anderson insulating phase to a metallic phase as the on-site repulsion U is increased beyond a critical value Uc. However, there appears to be no sharp signal of this metal-insulator transition in the screened site energies. We observe that, while the system remains metallic for interaction values up to twice Uc, the conductivity is maximal in the metallic phase just beyond Uc, and decreases for larger correlation.