Crossover from interaction induced localization to delocalization in disordered electron systems

TL;DR

This paper numerically studies how interactions and disorder influence electron transport, revealing a crossover from localization to delocalization depending on disorder strength.

Contribution

It introduces an efficient numerical method for analyzing large disordered interacting systems, capable of handling long-range interactions and providing insights into transport behavior.

Findings

Interactions enhance transport in strongly localized regimes.

Interactions suppress transport in weakly disordered regimes.

The study identifies a crossover from localization to delocalization driven by disorder and interactions.

Abstract

We numerically investigate the transport properties of interacting spinless electrons in disordered systems. We use an efficient method which is based on the diagonalization of the Hamiltonian in the subspace of the many-particle Hilbert space which is spanned by the low-energy Slater states. Low-energy properties can be calculated with an accuracy comparable to that of exact diagonalization but for larger system sizes. The method works well in the entire parameter space, and it can handle long-range as well as short-range interactions. Using this method we calculate the combined effect of disorder and interactions on the Kubo-Greenwood conductance and on the sensitivity of the ground state energy to a twist in the boundary conditions. We find that the influence of the interactions on the transport properties is opposite for large and small disorder. In the strongly localized regime (small kinetic energy, large disorder) interactions increase the transport whereas for weak disorder (large kinetic energy) interactions decrease the transport.