The University of Southampton
University of Southampton Institutional Repository

A disordered spin model with a quantum-induced phase transition related to Bose condensation in a random potential

A disordered spin model with a quantum-induced phase transition related to Bose condensation in a random potential
A disordered spin model with a quantum-induced phase transition related to Bose condensation in a random potential
The authors consider a random magnetic model which is related to Bose condensation in the presence of a random potential. It is an XY model with a random z field. The classical model always has an ordered ground state. The nature of the ground state is unusual: the main contribution to the spontaneous magnetisation comes from a dilute set of weakly interacting pairs of spins. Within each pair the spins are strongly coupled, so for low-energy dynamics only the motion of the total spin of the pair is relevant. This allows the construction of an effective Hamiltonian only involving the pairs' total spins. When this is semi-classically quantised via a 1/S expansion, they find that the zero-point spin wave motion destroys the magnetised ground state if either the number of spin states is sufficiently small (for fixed strength of disorder), or for sufficiently large disorder (for fixed number of spin states). Finally they discuss the relation of the model to the problem of Bose condensation in a random potential, where the interaction strength is related to the number of spin states in the spin model
0022-3719
5829-5837
Brackstone, M.A.
ec944365-2b0a-4f67-b331-936750d9d383
Gunn, S
d61115fe-7601-4f65-8929-1b4df2889eab
Brackstone, M.A.
ec944365-2b0a-4f67-b331-936750d9d383
Gunn, S
d61115fe-7601-4f65-8929-1b4df2889eab

Brackstone, M.A. and Gunn, S (1987) A disordered spin model with a quantum-induced phase transition related to Bose condensation in a random potential. Journal of Physics C: Solid State Physics, 20 (34), 5829-5837. (doi:10.1088/0022-3719/20/34/018).

Record type: Article

Abstract

The authors consider a random magnetic model which is related to Bose condensation in the presence of a random potential. It is an XY model with a random z field. The classical model always has an ordered ground state. The nature of the ground state is unusual: the main contribution to the spontaneous magnetisation comes from a dilute set of weakly interacting pairs of spins. Within each pair the spins are strongly coupled, so for low-energy dynamics only the motion of the total spin of the pair is relevant. This allows the construction of an effective Hamiltonian only involving the pairs' total spins. When this is semi-classically quantised via a 1/S expansion, they find that the zero-point spin wave motion destroys the magnetised ground state if either the number of spin states is sufficiently small (for fixed strength of disorder), or for sufficiently large disorder (for fixed number of spin states). Finally they discuss the relation of the model to the problem of Bose condensation in a random potential, where the interaction strength is related to the number of spin states in the spin model

Full text not available from this repository.

More information

Published date: December 1987

Identifiers

Local EPrints ID: 75533
URI: https://eprints.soton.ac.uk/id/eprint/75533
ISSN: 0022-3719
PURE UUID: 26db5d86-db42-40c2-acfc-00a11fdda9cb

Catalogue record

Date deposited: 11 Mar 2010
Last modified: 18 Jul 2017 23:42

Export record

Altmetrics

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of https://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×