Study of multiband disordered systems using the typical medium dynamical cluster approximation

TL;DR

This paper extends the typical medium dynamical cluster approximation to multiband disordered systems, enabling systematic analysis of disorder effects on electronic properties and applying it to real materials like K$_x$Fe$_{2-y}$Se$_2$.

Contribution

The authors develop an extended formalism for the typical medium dynamical cluster approximation tailored for multiband systems, allowing detailed study of disorder-induced localization phenomena.

Findings

Non-local correlation effects influence the density of states and mobility edge.

Application to K$_x$Fe$_{2-y}$Se$_2$ shows it is not an Anderson insulator despite strong disorder.

Results align with transfer matrix and kernel polynomial methods.

Abstract

We generalize the typical medium dynamical cluster approximation to multiband disordered systems. Using our extended formalism, we perform a systematic study of the non-local correlation effects induced by disorder on the density of states and the mobility edge of the three-dimensional two-band Anderson model. We include inter-band and intra-band hopping and an intra-band disorder potential. Our results are consistent with the ones obtained by the transfer matrix and the kernel polynomial methods. We apply the method to K$_x$Fe$_{2-y}$Se$_2$ with Fe vacancies. Despite the strong vacancy disorder and anisotropy, we find the material is not an Anderson insulator. Our results demonstrate the application of the typical medium dynamical cluster approximation method to study Anderson localization in real materials.