The effect of anisotropy of long-range hopping on localization in three-dimensional lattices

TL;DR

This paper investigates how anisotropy in long-range hopping affects localization in three-dimensional lattices, revealing that isotropic long-range hopping can lead to localization, while anisotropic hopping prevents it, extending previous 1D results.

Contribution

It demonstrates that cooperative shielding extends to 3D isotropic long-range hopping, but not to anisotropic cases, and analyzes how anisotropy influences localization phenomena.

Findings

Localization occurs in 3D isotropic long-range hopping with $eta=0$.

Anisotropic long-range hopping does not support localization.

The nature of states depends on $eta$ and isotropy, affecting ergodicity and localization.

Abstract

It has become widely accepted that particles with long-range hopping do not undergo Anderson localization. However, several recent studies demonstrated localization of particles with long-range hopping. In particular, it was recently shown that the effect of long-range hopping in 1D lattices can be mitigated by cooperative shielding, which makes the system behave effectively as one with short-range hopping. Here, we show that cooperative shielding, demonstrated previously for 1D lattices, extends to 3D lattices with isotropic long-range $r^{-\alpha}$ hopping, but not to 3D lattices with dipolar-like anisotropic long-range hopping. We demonstrate the presence of localization in 3D lattices with uniform ($\alpha=0$) isotropic long-range hopping and the absence of localization with uniform anisotropic long-range hopping by using the scaling behaviour of eigenstate participation ratios. We use the scaling behaviour of participation ratios and energy level statistics to show that the existence of delocalized, non-ergodic extended, or localized states in the presence of disorder depends on both the exponents $\alpha$ and the isotropy of the long-range hopping amplitudes.