Universal cross-over behavior of a magnetic impurity and consequences for doping in spin-1/2 chains

TL;DR

This paper investigates the universal crossover behavior of magnetic impurities in spin-1/2 chains, revealing how impurity susceptibility exhibits universal scaling and predicting observable two-channel Kondo effects in doped chains.

Contribution

It introduces a modified transfer-matrix DMRG method to analyze impurity effects and calculates universal crossover functions for susceptibility in spin chains.

Findings

Universal data-collapse of impurity susceptibility over temperature

Local susceptibilities show boundary effects and competition

Quantitative predictions for experimental observation of two-channel Kondo physics

Abstract

We consider a magnetic impurity in the antiferromagnetic spin-1/2 chain which is equivalent to the two-channel Kondo problem in terms of the field theoretical description. Using a modification of the transfer-matrix density matrix renormalization group (DMRG) we are able to determine local and global properties in the thermodynamic limit. The cross-over function for the impurity susceptibility is calculated over a large temperature range, which exhibits universal data-collapse. We are also able to determine the local susceptibilities near the impurity, which show an interesting competition of boundary effects. This results in quantitative predictions for experiments on doped spin-1/2 chains, which could observe two-channel Kondo physics directly.