Impurity-doping induced ferroelectricity in frustrated antiferromagnet CuFeO2

TL;DR

This study reveals that impurity doping in the frustrated antiferromagnet CuFeO2 induces ferroelectricity, with doping and magnetic fields controlling the magnetic and electric phase transitions, suggesting new ways to engineer multiferroic properties.

Contribution

It demonstrates that impurity doping can induce ferroelectricity in a frustrated antiferromagnet and elucidates the relationship between doping, magnetic structure, and ferroelectric behavior.

Findings

Ferroelectricity appears at zero magnetic field for x=0.02 doping.

The onset of ferroelectricity coincides with noncollinear magnetic structure.

Doping reduces the magnetic transition field to zero.

Abstract

Dielectric responses have been investigated on the triangular-lattice antiferromagnet CuFeO2 and its site-diluted analogs CuFe1-xAlxO2 (x=0.01 and 0.02) with and without application of magnetic field. We have found a ferroelectric behavior at zero magnetic field for x=0.02. At any doping level, the onset field of the ferroelectricity always coincides with that of the noncollinear magnetic structure while the transition field dramatically decreases to zero field with Al doping. The results imply the further possibility of producing the ferroelectricity by modifying the frustrated spin structure in terms of site-doping and external magnetic field.