Dielectric Anomaly in the Quasi-One-Dimensional Frustrated Spin-1/2 System Rb$_{2}$(Cu$_{1-x}$M$_{x}$)$_{2}$Mo$_{3}$O$_{12}$ (M=Ni and Zn)

TL;DR

This study investigates the dielectric and magnetic properties of a quasi-one-dimensional frustrated spin-1/2 system, revealing an anomalous low-temperature dielectric increase linked to magnetic behavior, suppressed by impurity doping.

Contribution

It demonstrates the connection between dielectric anomalies and magnetic fluctuations in a frustrated spin system, highlighting impurity effects on these properties.

Findings

Dielectric response increases below ~50 K and is suppressed by impurities.

Magnetic susceptibility shows short-range helical order suppressed by doping.

Dielectric anomaly is strongly correlated with magnetic susceptibility.

Abstract

Dielectric and magnetic properties have been studied for poly-crystalline samples of quasi-one-dimensional frustrated spin-1/2 system Rb$_{2}$(Cu$_{1-x}$M$_{x}$)$_{2}$Mo$_{3}$O$_{12}$(M=Ni and Zn) which does not exhibit a three-dimensional magnetic transition due to quantum spin fluctuation and low dimensionality. A broad peak in the magnetic susceptibility - temperature curves originated from a short range helical ordering at low temperature is suppressed by the Ni and Zn substitution for Cu sites. The capacitance is found to anomalously increase with decreasing T below ~50 K, which is also suppressed by the impurity doping. The behavior of the anomalous capacitance component is found to be strongly connected with that of the magnetic susceptibility for Rb$_{2}$(Cu$_{1-x}$M$_{x}$)$_{2}$Mo$_{3}$O$_{12}$ which indicates that the low-temperature dielectric response is driven by the magnetism.