Dimerized phase of ionic Hubbard models

Bosonization of dimerized Hubbard chains

The foundations of bosonization were laid more than 50 years ago in a seminal paper by Tomonaga [1]. During the following decades the method was worked out and successfully applied to one-dimensional electron and spin systems [2, 3, 4]. Despite its long history there are still some subtle points in the bosonization formalism which are not taken into consideration in the majority of the literatu...

Quantum Phase Transitions in a Dimerized Bose-Hubbard Model: A DMRG Study

We investigate the phase diagram of a dimerized Bose-Hubbard model, using density matrix renormalization group technique. We find a new phase, which is the coexistence of superfluid and bond-wave phases, due to the effect of dimerization. Experimentally dimerization in optical lattice can be realized by using two counter propagating laser beams of different wavelengths. Apart from the conventio...

Bosonization of Dimerized Spinless-fermion and Hubbard Chains

Random Phase Approximation for Multi-Band Hubbard Models

We derive the random-phase approximation for spin excitations in general multi-band Hubbard models, starting from a collinear ferromagnetic HartreeFock ground state. The results are compared with those of a recently introduced variational many-body approach to spin-waves in itinerant ferromagnets. As we exemplify for Hubbard models with one and two bands, the two approaches lead to qualitativel...

Phase transitions of the ionic Hubbard model on the honeycomb lattice

Many-body problem on the honeycomb lattice systems have been the subject of considerable experimental and theoretical interest. Here we investigate the phase transitions of the ionic Hubbard model on the honeycomb lattice with an alternate ionic potential for the half filling and hole doping cases by means of cellular dynamical mean field theory combining with continue time quantum Monte Carlo ...