Magnetic and dielectric properties in the langasite-type compounds : A3BFe3D2O14 with A=Ba, Sr, Ca, B=Ta, Nb, Sb and D=Ge, Si

TL;DR

This study investigates the structural, magnetic, and dielectric properties of Fe-based langasite compounds with various cation substitutions, revealing helical magnetic order and magnetoelectric coupling at low temperatures.

Contribution

It provides new insights into how cation substitutions affect magnetic and dielectric behaviors in Fe langasites, highlighting their magnetoelectric properties.

Findings

Helical magnetic order observed below 24-35 K.

Dielectric permittivity anomaly at magnetic transition.

Cation substitution influences magnetoelectric coupling.

Abstract

The Fe-based langasites are the first reported compounds presenting a magnetic ordering in this rich family, besides being well known for piezo-electric properties and optical activity. The structural, magnetic and dielectric properties of the Fe langasite compounds, with various substitution of non-magnetic cations, have been studied with x-ray and neutron diffraction, magnetostatic measurements, M\"ossbauer spectroscopy, and dielectric measurements. The title compounds (trigonal, space group P321) display a helical magnetic order with signatures of frustration below TN ~24- 35 K where an anomaly of the dielectric permittivity is observed. The influence of the cationic substitutions and the nature of the magnetoelectric coupling is hereafter addressed.