Magnetic and electric properties in the distorted tetrahedral spin chain system Cu3Mo2O9

TL;DR

This study investigates the multiferroic behavior of Cu3Mo2O9, revealing the coexistence of antiferromagnetic order and ferroelectricity at low temperatures, with phase diagrams influenced by magnetic field orientation.

Contribution

It provides the first detailed phase diagram of Cu3Mo2O9, demonstrating the interplay of magnetic frustration and low dimensionality in multiferroic properties.

Findings

Antiferromagnetic order occurs with ferroelectricity at 7.9 K.

Spontaneous electric polarization appears in the antiferromagnetic phase.

Multiple ferroelectric phases depend on magnetic field direction.

Abstract

We study the multiferroic properties in the distorted tetrahedral quasi-one dimensional spin system Cu$_3$Mo$_2$O$_9$, in which the effects of the low dimensionality and the magnetic frustration are expected to appear simultaneously. We clarify that the antiferromagnetic order is formed together with ferroelectric properties at $T_{\rm N}=7.9$ K under zero magnetic field and obtain the magnetic-field-temperature phase diagram by measuring dielectric constant and spontaneous electric polarization. It is found that the antiferromagnetic phase possesses a spontaneous electric polarization parallel to the c axis when the magnetic field $H$ is applied parallel to the a axis. On the other hand, there are three different ferroelectric phases in the antiferromagnetic phase for $H$ parallel to the c axis.