  A colossal electroresistance effect is observed around room temperature in a
transition metal oxide LuFe2O4. The measurements of resistance under various
applied voltages as well as the highly nonlinear current-voltage
characteristics reveal that a small electric field is able to drive the
material from the insulating state to a metallic state. The threshold field at
which the insulating-metallic transition occurs, decreases exponentially with
increasing temperature. We interpret this transition as a consequence of the
breakdown of the charge-ordered state triggered by applied electric field,
which is supported by the dramatic dielectric response in a small electric
field. This colossal electroresistance effect as well as the high dielectric
tunability around room temperature in low applied fields makes LuFe2O4 a very
promising material for many applications.
