Correlation-induced band suppression in the two-orbital Hubbard model

TL;DR

This paper investigates the effects of electron correlations on orbital behavior in a one-dimensional two-orbital Hubbard model, revealing how correlation can suppress bands and influence orbital occupancy and transitions.

Contribution

It provides the first detailed analysis of the two-orbital Hubbard model in 1D using DMRG, exploring scenarios of orbital-selective Mott transitions and band suppression.

Findings

Orbital densities and double occupancies are affected by electron interactions.

Finite inter-orbital hopping influences orbital form-factors.

The second scenario of orbital-selective Mott transition is observed in 1D.

Abstract

The orbital degrees of freedom are of vital importance in explanation of various phenomena. Among them is the orbital-selective Mott transition (OSMT), which is thought to occur in several materials as Ca$_{2-x}$Sr$_x$RuO$_4$ and La$_{n+1}$Ni${_n}$O$_{3n+1}$. OSMT is usually studied in the infinite-dimension limit, and for the time being, it is not clear if it could survive in one-dimensional (1D) case. There exist two scenarios for the OSMT: upon increasing the interaction in a two-band system i) one of the bands becomes insulating, while the other remains metallic and ii) one of the bands becomes empty, while the other may eventually undergo a single-band Mott insulator transition. In this work, we present a preliminary study of the two-orbital Hubbard model by means of Density Matrix Renormalization Group in 1D at quarter-filling, where the second scenario seems to be realized. In particular, we study the orbital densities, double occupancies and form-factors also in the case of finite inter-orbital inter-site hopping.