Gooth Johannes, Böhnert Tim, Gluschke Jan G, Hamdou Bacel, Barth Sven, Görlitz Detlef, Zierold Robert, Nielsch Kornelius
Institute of Applied Physics, Universität Hamburg, Jungiusstrasse 11, 20355 Hamburg, Germany.
J Phys Condens Matter. 2014 Nov 26;26(47):472202. doi: 10.1088/0953-8984/26/47/472202. Epub 2014 Oct 30.
In this work the kinetics of the charge ordering in magnetite (Fe3O4) below the Verwey transition temperature TV is investigated in time and energy domain. After excitation by a one-second voltage pulse to destruct the charge-ordered state below TV, an alternating current (AC) is used to perturb its recovery process. Upon warming up to above a temperature T(r)(< TV) 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 ΔE = 126 meV is extracted. Below Tr the real part of the ac conductance Greal follows the relation Greal ∼ f(α) with α = 0.98 ± 0.18, suggesting that the charge reordering is driven by correlated hopping transport. The relaxation time τ = 1/f(T(r)) of the charge-ordered state is determined for temperatures between 70 and 98 K and is extrapolated to τ(TV) = 1.6 ms, continuously slowing down its dynamics as the temperature is decreased.
在这项工作中，研究了在韦尔韦转变温度(T_V)以下磁铁矿（(Fe_3O_4)）中电荷有序化的动力学，涉及时间和能量领域。在通过一秒钟的电压脉冲激发以破坏低于(T_V)的电荷有序状态后，使用交流电（AC）来扰动其恢复过程。在升温至高于温度(T(r))（(< T_V)）时，尽管存在交流扰动，电荷有序仍会恢复，因为与温度相关的弛豫时间变得比交流的极性变化短。从(T(r)(f))的频率依赖性中，提取出激活能(\Delta E = 126)毫电子伏特。在(T_r)以下，交流电导率(G_{real})的实部遵循关系(G_{real} \sim f(\alpha))，其中(\alpha = 0.98 \pm 0.18)，这表明电荷重新排序是由相关的跳跃输运驱动的。确定了温度在70至98K之间的电荷有序状态的弛豫时间(\tau = 1/f(T(r)))，并外推至(\tau(T_V) = 1.6)毫秒，随着温度降低其动力学不断减慢。
