Dielectric Properties of Charge-Ordered LuFe2O4 Revisited: The Apparent Influence of Contacts

We show results of broadband dielectric measurements on the charge ordered, proposed to be multiferroic material LuFe2O4. The temperature and frequency dependence of the complex permittivity as investigated for temperatures above and below the charge-order transition near T-CO approximate to 320 K and for frequencies up to 1 GHz can be well described by a standard equivalent-circuit model considering Maxwell-Wagner-type contacts and hopping induced ac conductivity. No pronounced contribution of intrinsic dipolar polarization could be found, and thus the ferroelectric character of the charge order in LuFe2O4 has to be questioned.