Origin of multiferroism in the charge frustrated LuFe2O4 compound

• We propose a microscopic model to study the multiferroic properties of LuFe2O4 (LFO).
• The dielectric function ϵ   of LFO has a plateau near TN=240K.
• At room temperature ϵ decreases by applying an external magnetic field.
• This behavior is an evidence for a strong coupling of spins and electric dipoles.
• The phonon energy and damping of the Eg3 mode show kinks at TCOTCO and TNTN.

We propose a microscopic model in order to study the multiferroic properties of LuFe2O4. It is shown that the real part of the dielectric constant ϵ   has a plateau near the magnetic phase transition TN=240K. At room temperature ϵ decreases strongly by applying an external magnetic field H  . This behavior is an evidence for a strong coupling of spins and electric dipoles in agreement with the experimental data. The observed kinks in the temperature dependence of the phonon energy and damping for the Eg3 mode around the ferroelectric and ferrimagnetic transition temperatures show that this phonon mode is closely related to the structural, magnetic and ferroelectric properties of LuFe2O4.