Models of impurities in valence bond spin chains and ladders

TL;DR

This paper introduces exactly solvable models of impurities in valence bond spin chains and ladders, revealing the absence of local enhancement of antiferromagnetic correlations around impurities.

Contribution

It provides a new class of exactly solvable impurity models in AKLT-type spin chains and ladders, expanding understanding of impurity effects in these systems.

Findings

Ground states with impurities can be found exactly

Local enhancement of antiferromagnetic correlations is absent in these models

Models include S=1/2 impurities in S=1 AKLT chains and ladders

Abstract

We present the class of models of a nonmagnetic impurity in S=1/2 generalized ladder with an AKLT-type valence bond ground state, and of a S=1/2 impurity in the S=1 AKLT chain. The ground state in presence of impurity can be found exactly. Recently studied phenomenon of local enhancement of antiferromagnetic correlations around the impurity is absent for this family of models.