Temperature dependence of local states due to S=1/2 impurities and their correlation in a S=1 Heisenberg chain

TL;DR

This paper investigates how local magnetic states caused by impurities in an S=1 Heisenberg chain change with temperature, revealing that magnetization profiles persist at higher temperatures while correlations weaken, using a novel quantum Monte-Carlo method.

Contribution

It introduces a loop cluster quantum Monte-Carlo method with fixed magnetization to study impurity-induced local states and their correlations in a Heisenberg chain.

Findings

Magnetization profiles remain visible at higher temperatures.

Two-point correlations are weakly affected by temperature.

Small energy gaps between quasi-degenerate impurity states are identified.

Abstract

We study the temperature dependence of the low temperature spin configurations, investigating the magnetization profile of the local states due to the impurities and the two point correlation function centered in one of the impurities. This correlation is found to be weak against temperature effects although the magnetization profile in the triplet state is visible up to higher temperatures. Here we introduce a loop cluster quantum Monte-Carlo method with a fixed magnetization Mz in order to study the correlations in the ground state of a given value of Mz. From the population distribution of magnetization, the very small energy gap between the quasi degenerate states due to the impurities is obtained.