一维二元非对角关联无序体系交流跳跃电导特性  

Characteristic of alternating current hopping conductivity in one-dimensional binary disordered system with off-diagonal correlations

作　　者：马松山[1] 徐慧[1] 李燕峰[1] 张鹏华[1] 

机构地区：[1]中南大学物理科学与技术学院,长沙410083

出　　处：《物理学报》2007年第9期5394-5399,共6页Acta Physica Sinica

基　　金：高等学校博士学科点专项科研基金(批准号:20020533001);湖南省自然科学基金(批准号:05JJ40135)资助的课题.~~

摘　　要：在单电子紧束缚无序模型基础上,建立了一维二元非对角关联无序体系电子跳跃输运交流电导模型,并推导了其交流电导公式,通过计算其交流电导率,探讨了格点能量无序度、格点原子组分、非对角关联及温度、外场对体系交流跳跃电导的影响.计算结果表明,一维二元非对角关联无序体系的交流电导率随格点能量无序度的增大而减小.同时,体系中两种原子的组分的变化实际代表着体系成分无序程度的变化,因而对其交流电导率的影响很大,表现为随A类原子含量p的增加而先减小后增大.当引入非对角关联时,体系出现退局域化现象,电子波函数由局域态向扩展态发展,从而使体系的交流电导率大于Anderson模型情况下体系的电导率.此外,温度对一维二元非对角关联无序体系的电子输运的影响表现为体系的交流电导率随温度的升高而减小,而外加交变电场对体系交流电导率的影响表现为随外场频率的升高而增大很快.Based on a tight-binding disordered model describing a single electron band, we establish a model of one-dimensional binary disordered systems with off-diagonal correlations, and derive the alternating current （ac） conductance formula. By calculating the ac conductivity, the function of disorder and off-diagonal correlations in electronic transport are analyzed, and the dependence of the ac conductivity on the field frequency and the temperature is studied. The results indicate that the ac conductivity of one-dimensional binary disordered system decreases with the increasing of the degree of lattices energy disorder. And the ac conductivity of the system is also dependent on the probabilities p, which represents the degree of compositional disorder of the system to some extent. The ac conductivity of system first decreases with the increasing of p, then increases with farther increasing of p. We also find that off-diagonal correlations lead to delocalization and enhance the ac conductivity of the system,namely, the ac conductivity of one-dimensional binary disordered system with off-diagonal correlations is larger than that of uncorrelated system in the Anderson limit. Moreover, the ac conductivity of one-dimensional binary disordered system decreases with the increasing of temperature, and increases drastically with the increasing of the frequency of the electric field.

关 键 词：二元无序体系 交流跳跃电导 格点能量无序度 非对角关联 

分 类 号：O561[理学—原子与分子物理]