Direct evidence for intermediate multiferroic phase in LiCuFe2(VO4)3

TL;DR

This study provides direct evidence of an intermediate multiferroic phase in LiCuFe2(VO4)3, revealing complex magnetic and electric behaviors associated with two antiferromagnetic transitions and strong magnetoelectric coupling.

Contribution

It reports the discovery of an intermediate multiferroic phase in LiCuFe2(VO4)3 with detailed experimental characterization of its magnetic and electric properties.

Findings

Two antiferromagnetic transitions at ~10 K and ~8.2 K.

Dielectric peak and ferroelectricity at the first transition.

Suppressed electric polarization under magnetic field.

Abstract

Magnetic susceptibility, specific heat, dielectric, and electric polarization of LiCuFe2(VO4)3 have been investigated. Two sequential antiferromagnetic transitions at TN1 ~ 9.95 K and TN2 ~ 8.17 K are observed under zero magnetic field. While a dielectric peak at TN1 is clearly identified, the measured pyroelectric current also exhibits a sharp peak at TN1, implying the magnetically relevant ferroelectricity. Interestingly, another pyroelectric peak around TN2 with opposite signal is observed, resulting in the disappearance of electric polarization below TN2. Besides, the electric polarization is significantly suppressed in response to external magnetic field, evidencing remarkable magnetoelectric effect. These results suggest the essential relevance of the magnetic structure with the ferroelectricity in LiCuFe2(VO4)3, deserving for further investigation of the underlying mechanism.