Dielectric responses have been investigated on the triangular-lattice antiferromagnet CuFe O2 and its site-diluted analogs Cu Fe1-x Alx O2 (x=0.01 and 0.02) with and without the application of the 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 frustrated spin structure in terms of site doping and external magnetic field.
|Physical Review B - Condensed Matter and Materials Physics
|Published - 2007 Mar 27