Electric field dependence of magnetic correlation in magneto-electric multiferroic CuFe1-xAlxO2

Abstract

Magneto-electric (ME) multiferroic CuFeO2 and slightly diluted CuFe1-xAlxO2 are rare examples of ME-multiferroics whose ferroelectricity originates from the 'proper-screw' type magnetic ordering. Recent polarized neutron diffraction studies have revealed that there is a one-to-one correspondence between the spin helicity and the polarity of induced ferroelectric polarization. In the present study, we have performed unpolarized neutron diffraction measurements under applied poling electric field up to ∼ 2.2 MV/m using CuFe1-xAlxO 2 (x = 0.02) sample, which undergoes ferroelectric transition at Tc ∼ 7 K in zero magnetic field. The present results revealed that the shape of the magnetic diffraction profile in the ferroelectric phase significantly depends on applied poling electric field, while the integrated intensity of the magnetic reflection does not. This implies that the poling electric field affects the magnetic correlation through the local ME-coupling in this system. © 2010 IOP Publishing Ltd.