Phase phonon spectrum and melting in a quantum rotor model with diagonal disorder
Abstract
We study the zero-temperature () quantum rotor model with on-site disorder in the charging energy. Such a model may serve as an idealized Hamiltonian for an array of Josephson-coupled small superconducting grains, or superfluid He in a disordered environment. In the approximation of small-amplitude phase fluctuations, the Hamiltonian maps onto a system of coupled harmonic oscillators with on-site disorder. We study the effects of disorder in this harmonic regime, using the coherent potential approximation (CPA), obtaining the density of states and the lifetimes of the spin-wave-like excitations for several choices of the parameters which characterize the disorder. Finally, we estimate the parameters characterizing the quantum melting of the phase order, using a suitable Lindemann criterion.
Keywords
Cite
@article{arxiv.cond-mat/0211539,
title = {Phase phonon spectrum and melting in a quantum rotor model with diagonal disorder},
author = {W. A. Al-Saidi and D. Stroud},
journal= {arXiv preprint arXiv:cond-mat/0211539},
year = {2009}
}
Comments
8 pages, 5 figures. To be published in Phys. Rev. B. Minor changes