Eur. Phys. J. B (2013) 86: 446
https://doi.org/10.1140/epjb/e2013-40336-4

Regular Article

Correlation functions in one-dimensional spin lattices with Ising and Heisenberg bonds

¹ INFN-Laboratori Nazionali di Frascati, Via E. Fermi 40, 00044 Frascati, Italy
² Department of Theoretical Physics, Yerevan State University, Alex Manoogian 1, 0025 Yerevan, Armenia
³ ICTP, Strada Costiera 11, 34151 Trieste, Italy

^a e-mail: ohanyan@yerphi.am

Received: 11 April 2013
Received in final form: 25 July 2013
Published online: 1 November 2013

Abstract

A general technique of exact calculation of any correlation functions for the special class of one-dimensional spin models containing small clusters of quantum spins assembled to a chain by alternating with the single Ising spins is proposed. The technique is a natural generalization of that in the models solved by a classical transfer matrix. The general expressions for corresponding matrix operators which are the key components of the technique are obtained. As it is clear from the general principles, the decay of the correlation functions of various types is explicitly shown to be governed by a single correlation length. The technique is illustrated by two examples: symmetric diamond chain and asymmetric sawtooth chain.