Interaction effects between impurities in low-dimensional spin- antiferromagnets

¹ Department of Physics, Chalmers University of Technology S-412 96 Göteborg, Sweden
² Department of Physics, University of Kaiserslautern D-67663 Kaiserslautern, Germany

Received: 15 September 2005
Accepted: 18 November 2005

Abstract

We are considering the interplay between several non-magnetic impurities in the spin-(1/2) Heisenberg antiferromagnet in chains, ladders and planes by introducing static vacancies in numerical quantum Monte Carlo simulations. The effective potential between two and more impurities is accurately determined, which gives a direct measure of the quantum correlations in the systems. Large effective interaction potentials are an indication of strong quantum correlations in the system and reflect the detailed nature of the valence bond ground states. In two-dimensions (2D) the interactions are smaller, but can still be analyzed in terms of valence bonds.