Suppression of Spin Frustration due to Orbital Selection

TL;DR

This paper investigates how orbital degrees of freedom influence spin frustration in geometrically frustrated systems, revealing a spontaneous orbital selection that reduces the system to a less frustrated one.

Contribution

It demonstrates that orbital selection can suppress spin frustration, leading to a self-organization phenomenon in multi-orbital systems.

Findings

Spin correlation extends in the ladder lattice.

Spin excitation is confined in one side of the double chain in zigzag.

Orbital selection reduces the system to a less frustrated state.

Abstract

In order to clarify a crucial role of orbital degree of freedom in geometrically frustrated systems, we investigate both ground- and excited-state properties of the e_g-orbital degenerate Hubbard model on two kinds of lattices, ladder and zigzag chain, by using numerical techniques. In the ladder, spin correlation extends on the whole system, while the zigzag chain is decoupled to a double chain and spin excitation is confined in one side of the double chain due to the selection of a specific orbital. We envision a kind of self-organization phenomenon that the geometrically frustrated multi-orbital system is spontaneously reduced to a one-orbital model to suppress the spin frustration.