Magnetic and electric field effects on the magnetic and charge order in a multiferroic LuFe2O4

Jinsheng Wen (Brookhaven National Lab)

LuFe2O4 is a new multiferroic material where the ferroelectric polarization originates from charge valence order of Fe2+ and Fe3+ ions instead of cation displacements, which starts to appear at temperatures above the magnetic ordering temperature. We have observed interesting magnetic/electric field effects on the charge and magnetic orders with neutron scattering measurements. In an external magnetic field, we found that the charge order is suppressed in the magnetically disordered phase. As a result, the dielectric constant is also reduced. The magnetic field effect on the charge order suggests a different path through which one could affect ferroelectric properties in multiferroic materials, and reveals the existence of a possible new mechanism for the coupling of magnetic and ferroelectric orders in LuFe2O4. With the application of an electric field/current, both the charge and magnetic orders appear to be robust and remain intact, when the internal heating effect due to current running through the sample has been taken into account. This explains the electric field effects on the material's properties and the non-Ohmic behavior reported by other groups. Overall, LuFe2O4 is unique in the sense that the charge order is sensitive to magnetic field even in the non-magnetic state, while it is on the other hand, not electrically sensitive.

Back to Seminar Home Page

Last modified 06-November-2009 by website owner: NCNR (attn: )