Formation of the S=1 paramagnetic centers in the bond-diluted spin-gap magnet

TL;DR

This study investigates how non-magnetic bond doping in a spin-gap magnet creates S=1 paramagnetic centers, revealing their concentration dependence and coexistence with triplet excitations through ESR experiments.

Contribution

It demonstrates the formation and behavior of S=1 paramagnetic centers induced by bond doping in a specific spin-gap magnet, providing new insights into impurity effects.

Findings

Paramagnetic centers form due to bond doping.

Their concentration scales quadratically with impurity content.

Coexistence of local centers and triplet excitations observed.

Abstract

Electron spin resonance experiment reveals that non-magnetic bond doping of the spin-gap magnet (C$_4$H$_{12}$N$_2$)Cu$_2$Cl$_6$ (abbreviated PHCC) results in the formation of $S=1$ paramagnetic centers that dominate low-temperature ESR response. We have followed evolution of this signal with doping impurity content and have found that these centers concentration is quadratic over the impurity content. We also observe coexistence of the ESR responses from these local centers and from delocalized triplet excitations over certain temperature range.