Covalency driven modulation of paramagnetism and development of lone pair ferroelectricity in multiferroic Pb$_3$TeMn$_3$P$_2$O$_{14}$

TL;DR

This study explores how covalency influences the multiferroic properties of Pb$_3$TeMn$_3$P$_2$O$_{14}$, revealing a structural phase transition that induces ferroelectricity and modulates magnetic behavior while maintaining paramagnetism.

Contribution

It demonstrates the role of metal-oxygen covalency and structural phase transition in inducing multiferroicity and modulating magnetic properties in a Pb-based langasite compound.

Findings

Structural phase transition occurs above room temperature.

The compound becomes ferroelectric below 310 K.

Magnetic response is modulated without losing paramagnetism.

Abstract

We have investigated the structural, magnetic and dielectric properties of Pb-based langasite compound Pb$_3$TeMn$_3$P$_2$O$_{14}$ both experimentally and theoretically in the light of metal-oxygen covalency, and the consequent generation of multiferroicity. It is known that large covalency between Pb 6$p$ and O 2$p$ plays instrumental role behind stereochemical lone pair activity of Pb. The same happens here but a subtle structural phase transition above room temperature changes the degree of such lone pair activity and the system becomes ferroelectric below 310 K. Interestingly, this structural change also modulates the charge densities on different constituent atoms and consequently the overall magnetic response of the system while maintaining global paramagnetism behavior of the compound intact. This single origin of modulation in polarity and paramagnetism inherently connects both the functionalities and the system exhibits mutiferroicity at room temperature.