Anderson-Mott transition in a disordered Hubbard model with correlated hopping

Abstract

We study the ground state phase diagram of the Anderson-Hubbard model with correlated hopping at half filling in one-dimension. The Hamiltonian has a local Coulomb repulsion $U$ and a disorder potential with local energies randomly distributed in the interval $(-W,+W)$ with equal probability, acting on the singly occupied sites. The hopping process which modifies the number of doubly occupied sites is forbidden. The hopping between nearest-neighbor singly occupied and empty sites or between singly occupied and doubly occupied sites have the same amplitude $t$. We identify three different phases as functions of the disorder amplitude $W$ and Coulomb interaction strength $U>0$. When $U<4t$ the system shows a metallic phase (i) only when no disorder is present $W=0$ or an Anderson-localized phase (ii) when disorder is introduced $W\ne 0$. When $U>4t$ the Anderson-localized phase survives as long as disorder effects dominates on the interaction effects, otherwise a Mott insulator phase (iii) arises. The phases (i) and (ii) are characterized by a finite density of doublons and a vanishing charge gap between the ground state and the excited states. The phase (iii) is characterized by vanishing density of doublons and a finite gap for the charge excitations.

7 pages, 4 figures