Kinetics of the charge ordering in magnetite below the Verwey temperature

In this work the kinetics of the charge ordering in magnetite (Fe3O4) below the Verwey transition temperature T-V is investigated in time and energy domain. After excitation by a one-second voltage pulse to destruct the charge-ordered state below T-V, an alternating current (AC) is used to perturb its recovery process. Upon warming up to above a temperature T-r(< T-V) the charge order recovers despite the ac perturbation, because the temperature-dependent relaxation time becomes shorter than the polarity change of the ac. From the frequency dependence of T-r(f), an activation energy of Delta E = 126 meV is extracted. Below T-r the real part of the ac conductance G(real) follows the relation G(real) similar to f(alpha) with alpha = 0.98 +/- 0.18, suggesting that the charge reordering is driven by correlated hopping transport. The relaxation time tau = 1/f (T-r) of the charge-ordered state is determined for temperatures between 70 and 98 K and is extrapolated to tau (T-V) = 1.6 ms, continuously slowing down its dynamics as the temperature is decreased.