Emergence and spectral-weight transfer of electronic states in the Hubbard ladder

TL;DR

This study investigates how electronic states in a Hubbard ladder evolve with electron density, revealing emergent states and spectral-weight transfer that influence Mott physics and electronic band behavior.

Contribution

It demonstrates the emergence and spectral-weight transfer of electronic states in a Hubbard ladder as a function of electron density using advanced numerical methods.

Findings

A low-electron-density mode gains spectral weight with increasing density.

The antibonding band disappears at the Mott transition at half-filling.

Electronic states responsible for the Mott transition are identified.

Abstract

The number of electronic bands is usually considered invariant regardless of the electron density in a band picture. However, in interacting systems, the spectral-weight distribution generally changes depending on the electron density, and electronic states can even emerge or disappear as the electron density changes. Here, to clarify how electronic states emerge and become dominant as the electron density changes, the spectral function of the Hubbard ladder with strong repulsion and strong intrarung hopping is studied using the non-Abelian dynamical density-matrix renormalization-group method. A mode emerging in the low-electron-density limit gains spectral weight as the electron density increases and governs the dimer Mott physics at quarter-filling. In contrast, the antibonding band, which is dominant in the low-electron-density regime, loses spectral weight and disappears at the Mott transition at half-filling, exhibiting the momentum-shifted magnetic dispersion relation in the small-doping limit. This paper identifies the origin of the electronic states responsible for the Mott transition and brings a new perspective to electronic bands by revealing the overall nature of electronic states over a wide energy and electron-density regime.