无序材料直流电导中的无序作用机理

来源期刊：中南大学学报(自然科学版)2006年第4期

论文作者：马松山 徐慧 刘小良 肖剑荣

文章页码：655 - 659

关键词：无序材料;对角无序;非对角无序;完全无序;直流电导率

Key words：disordered materials; diagonal disorder; off-diagonal disorder; both diagonal and off-diagonal disorder; direct current conductivity

摘    要：在单电子紧束缚无序模型基础上,建立一维无序材料电子跳跃输运直流电导率计算模型,并推导其直流电导率计算公式;通过计算材料的直流电导率,分析不同无序形式下无序度对材料直流电导率的影响,探讨无序在材料电子输运中的本质作用。计算结果表明,在对角无序情况下,无序材料的直流电导率随着无序度的增加而减小;当无序度较小时,电导率随材料无序度的变化有振荡行为;非对角无序材料的电导率小于对角无序材料的电导率,同时,在无序度较小的区域,材料的电导率呈现先增大后减小的特性;完全无序材料的电导率大于非对角无序材料的电导率而小于对角无序材料的电导率,且在完全无序情况下材料的电导率随无序度的变化关系与非对角无序情况下电导率随无序度的变化关系很相似;在无序度较大时,无论是对角无序、非对角无序还是完全无序情况下,无序度对电导率的影响均不明显。

Abstract: Based on tight-binding disordered model, a direct current electronic hopping transport conductance model of one-dimensional disordered system was established, and the direct current conductivity formula was derived. By calculating the direct current conductivity of different disordered states, the relationship between the disorder and conductivity was analyzed, and the role of disorder in direct current conductivity of disordered materials was discussed. The results show that the direct current conductivity decreases with the increase of the degree of disorder in diagonal disordered system, and there is oscillatory property in weak disorder region. The conductivity of off-diagonal disordered systems is smaller than that of the diagonal disordered systems, and the conductivity increases first and then decreases with the increase of the degree disorder. In both diagonal and off-diagonal disordered systems, the conductivity is greater than that of off-diagonal disordered system, but smaller than that of the diagonal disordered system. In strong disorder region, the effect of disorder on the conductivity in three disorder modes is not obvious.