Renormalization group approach to the one-dimensional 1/4-filled Hubbard model with alternating on-site interactions

TL;DR

This paper uses renormalization group techniques to analyze a one-dimensional 1/4-filled Hubbard model with alternating on-site interactions, revealing how these interactions induce gaps and various ordered phases.

Contribution

It introduces a detailed renormalization group analysis of the 1/4-filled Hubbard model with alternating interactions, highlighting the emergence of gaps and phase transitions.

Findings

Presence of charge and spin gaps depending on interaction parameters

Tendency towards superconducting or antiferromagnetic order at zero temperature

Role of nearest and next-nearest neighbor interactions in phase behavior

Abstract

The one-dimensional Hubbard model with different on-site interactions is investigated by renormalization group technique. In the case of a 1/4-filled band the dynamical nonequivalence of sites leads to the appearance of Umklapp processes in the system and to the dynamical generation of a gap in the charge excitation spectrum for $U_{a}\not=U_{b}$, $U_{a}>0$ or $U_{b}>0$. The ground-state phase diagram is obtained in the limit of second order renormalization. Depending on the sign and relative values of the bare coupling constants, there is a gap in the spin or charge excitation spectrum and the model system tends to superconducting or antiferromagnetic order at T=0, with doubled period. The role of interaction between particles on nearest and next-nearest neighbor sites is also considered.