Non-perturbative analysis of impurity effects on the Kubo conductivity of nano to macroscopic structures

Abstract

ABSTRACTThe presence of impurities in solids is a source of many interesting effects, particularly relevant in the conductivity, optical properties and specific heat. For instance, in nano-electronics these effects could be useful to develop molecular devices such as novel computer architectures, chemical and biomedical sensors. However, the inclusion of impurities breaks the translational symmetry, restricting the systems that can be addressed theoretically in an exact way to those of few atoms. In this work, we present an alternative way to study the electrical conductance in real-space by means of a renormalization plus convolution method applied on the Kubo-Greenwood formula for multidimensional systems of macroscopic size with site and bond impurities. The results show that the spectral average of conductivity depends strongly on the location of site and bond impurities in periodic chains. Particularly, when the distance between impurities follows the Fibonacci sequence, we find that the spectral average falls following a power law as the number of atoms in the system grows. Finally, we analyze the impurity effects on the conductance spectra of periodic core-shell nanowires with a macroscopic length and periodic and quasiperiodically located impurities.