Eur. Phys. J. B (2016) 89: 106
https://doi.org/10.1140/epjb/e2016-60331-5

Regular Article

Phase diagrams of bosonic AB_n chains

¹ Departamento de Ciencias Básicas, Universidad Santo Tomas, Bogotá, Colombia
² Departamento de Física, Universidad Nacional de Colombia, Bogotá, Colombia

^a e-mail: jsilvav@unal.edu.co

Received: 27 April 2015
Received in final form: 23 September 2015
Published online: 20 April 2016

Abstract

The AB_{N − 1} chain is a system that consists of repeating a unit cell with N sites where between the A and B sites there is an energy difference of λ. We considered bosons in these special lattices and took into account the kinetic energy, the local two-body interaction, and the inhomogenous local energy in the Hamiltonian. We found the charge density wave (CDW) and superfluid and Mott insulator phases, and constructed the phase diagram for N = 2 and 3 at the thermodynamic limit. The system exhibited insulator phases for densities ρ = α/N, with α being an integer. We obtained that superfluid regions separate the insulator phases for densities larger than one. For any N value, we found that for integer densities ρ, the system exhibits ρ + 1 insulator phases, a Mott insulator phase, and ρ CDW phases. For non-integer densities larger than one, several CDW phases appear.