Spin-charge-orbital ordering on triangle-based lattices

TL;DR

This study explores how orbital degeneracy and anisotropy influence spin frustration and ordering in a zigzag chain Hubbard model, revealing a transition from decoupled chains to frustrated spin states.

Contribution

It demonstrates the impact of orbital level splitting on spin frustration and ordering in a zigzag chain Hubbard model using DMRG.

Findings

Orbital degeneracy decouples the zigzag chain into two spin chains.

Increasing orbital level splitting revives spin frustration.

A transition in spin incommensurability occurs with changing orbital anisotropy.

Abstract

We investigate the ground-state property of an e_g-orbital Hubbard model at quarter filling on a zigzag chain by exploiting the density matrix renormalization group method. When two orbitals are degenerate, the zigzag chain is decoupled to a doble-chain spin system to suppress the spin frustration due to the spatial anisotropy of the occupied orbital. On the other hand, when the level splitting is increased and the orbital anisotropy disappears, a characteristic change in the spin incommnsurability is observed due to the revival of the spin frustration.