Band structure picture for topology in strongly correlated systems with the ghost Gutzwiller ansatz

TL;DR

This paper introduces the ghost Gutzwiller variational framework to effectively analyze and interpret topological phases in strongly correlated systems, bridging a gap between band theory and correlation effects.

Contribution

The work develops a novel embedding method that provides an interpretable, efficient way to study correlated topological phases with direct experimental relevance.

Findings

Reproduces known results for the interacting BHZ model.

Reveals topologically nontrivial Hubbard bands with edge states.

Shows potential for manipulating topological features via magnetization.

Abstract

Understanding the interplay between electronic correlations and band topology remains a central challenge in condensed matter physics, primarily hindered by a language mismatch problem. While band topology is naturally formulated within a single-particle band theory, strong correlations typically elude such an effective one-body description. In this work, we bridge this gap leveraging the ghost Gutzwiller (gGut) variational embedding framework, which introduces auxiliary quasiparticle degrees of freedom to recover an effective band structure description of strongly correlated systems. This approach enables an interpretable and computationally efficient treatment of correlated topological phases, resulting in energy- and momentum-resolved topological features that are directly comparable with experimental spectra. We exemplify the advantages of this framework through a detailed study of the interacting Bernevig-Hughes-Zhang model. Not only does the gGut description reproduce established results, but it also reveals previously inaccessible aspects: most notably, the emergence of topologically nontrivial Hubbard bands hosting their own edge states, as well as possible ways to manipulate these through a finite magnetization. These results position the gGut framework as a promising tool for the predictive modeling of correlated topological materials.