Biased dielectric response in LuFe2O4

A complex permittivity at a low level of excitation signal was measured in ceramic LuFe2O4. A Debye-type relaxation response with a strong temperature dependence of a characteristic frequency was observed in accordance with earlier works. A small DC bias of about 10 V/cm led to unusual changes in the dielectric response. At frequencies, which were lower than the characteristic one, the conductivity drastically increased with slight decrease of the real part of the permittivity under the bias. In the opposite case of low frequencies, there are no traces of the DC bias effect. We show that an inhomogeneous charge distribution over surface layer (domain structure) is essential for describing the biased dielectric response in LuFe2O4.