TITLE:
A Numerical Study of the Effect of Disorder on Optical Conductivity in Inhomogeneous Superconductors
AUTHORS:
Long He, Jian Sun, Cunjun Yang, Yun Song
KEYWORDS:
Inhomogeneous Superconductor; Disorder Effect; Anderson Localization; Kernel Polynomial Method; Lanczos Method
JOURNAL NAME:
Journal of Modern Physics,
Vol.4 No.6A,
June
25,
2013
ABSTRACT:
We present the effect of disorder on the optical conductivity of two-dimensional inhomogeneous superconductors by applying the kernel polynomial method to solve the Bogoliubov-de Gennes equations. By means of the lattice size scaling of the generalized inverse participation ratio, we find that the localization length of the quasiparticle decreases significantly with the increase of the disorder strength. Meanwhile, the weak disorder can readily restrain the Drude weight, while the superconducting gap has the tendency to suppress the low-energy optical conductivity. We also employ the Lanczos exact diagonalization method to study the competition between the on-site repulsive interactions and disorder. It is shown that the screening effect of repulsive interactions significantly enhances the Drude weight in the normal phase.