Dilution Effects in Two-dimensional Quantum Orbital System

TL;DR

This paper investigates how dilution impacts the directional orbital order in a two-dimensional quantum orbital system, revealing quantum effects that enhance robustness against dilution compared to spin models.

Contribution

It introduces a quantum Monte Carlo study of dilution effects in a 2D orbital compass model, highlighting quantum effects that stabilize directional order.

Findings

Dilution reduces the orbital ordering temperature more than in spin models.

Quantum effects increase the effective dimensionality, making the order more robust.

Directional order persists despite dilution due to quantum enhancement.

Abstract

We study dilution effects in a Mott insulating state with quantum orbital degree of freedom, termed the two-dimensional orbital compass model. This is a quantum and two-dimensional version of the orbital model where the interactions along different bond directions cause frustration between different orbital configurations. A long-range correlation of a kind of orbital at each row or column, termed the directional order, is studied by means of the quantum Monte-Carlo method. It is shown that decrease of the ordering temperature due to dilution is much stronger than that in spin models. Quantum effect enhances the effective dimensionality in the system and makes the directional order robust against dilution. We discuss an essential mechanism of the dilute orbital systems.