Alloatti Luca
NEST-INFM, Università di Pisa and Scuola Normale Superiore, I-56126 Pisa, Italy. Max-Planck Institut für Metallforschung, Heisenbergstraße 3, 70569 Stuttgart, Germany.
J Phys Condens Matter. 2009 Jan 28;21(4):045503. doi: 10.1088/0953-8984/21/4/045503. Epub 2008 Dec 19.
This work shows that delocalization phenomena in single-electron quasi-one-dimensional quantum chains may occur at points different from the center of the energy spectrum (E = 0) and in systems lacking the symmetry [Formula: see text]. It is found that the peaks appearing in the average conductance are controlled by the band structure of the periodic system underlying the disorder. The average conductance is expanded in powers of the disorder strength, allowing the conductance to be redefined as the sum of a regular and an anomalous contribution. The first non-vanishing term of the anomalous part is of the fourth order. The fourth-order term can be calculated for any number of coupled chains in terms of a matrix expression. For strictly one-dimensional systems the expansion is calculated up to the 12th order for both diagonal and real off-diagonal disorder and is compared with the numerical data. It is also found that the anomalous contribution defined here is responsible for an even-odd effect of the average conductance.
这项工作表明，单电子准一维量子链中的离域现象可能发生在与能谱中心（E = 0）不同的点，并且发生在缺乏[公式：见正文]对称性的系统中。研究发现，平均电导中出现的峰值受无序底层周期系统的能带结构控制。平均电导按无序强度的幂次展开，从而可将电导重新定义为规则贡献与反常贡献之和。反常部分的首个非零项为四阶项。四阶项可以用矩阵表达式针对任意数量的耦合链进行计算。对于严格的一维系统，针对对角无序和实非对角无序，展开式计算到了十二阶，并与数值数据进行了比较。还发现，此处定义的反常贡献导致了平均电导的奇偶效应。
