One-dimensional physics in transition-metal nanowires: Renormalization group and bosonization analysis

TL;DR

This paper investigates the phase diagrams and ground states of a one-dimensional two-orbital Hubbard model relevant to transition-metal nanowires, using renormalization group and bosonization techniques to reveal new insulating states and effects of orbital degeneracy.

Contribution

It introduces a comprehensive analysis of the two-orbital Hubbard model with pair-hopping, highlighting the role of orbital symmetry and degeneracy in quantum phase transitions.

Findings

Identification of new insulating states due to pair-hopping and orbital symmetry

Effects of orbital degeneracy and velocity differences on phase diagrams

Ground state analysis for spin-polarized cases

Abstract

We study the one-dimensional two-orbital Hubbard model with general local interactions including a pair-hopping term. The model might be realized in one-dimensional transition-metal nanowires. Phase diagrams at T=0 are obtained by numerical integration of renormalization group equations and bosonization. Particular attention is paid to the effects of orbital degeneracy (or near-degeneracy), interactions favoring locally high-spin configurations, and velocity differences. Dynamical symmetry enlargement and duality approaches are employed to determine ground states and to understand quantum phase transitions between them. An important result is that the pair-hopping term and associated orbital symmetry can lead to new insulating states. The ground state for spin-polarized case is also discussed.