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 mul- tiferroic material LuFe2O4. The temperature and frequency dependence of the complex permittivity as investigated for temperatures above and below the charge-oder transition near T_CO ~ 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. 
Daniel Niermann, Florian Waschkowski, Joost de Groot, Manuel Angst,   and Joachim Hemberger
cond-mat.str-el