Point Defects in Two-Dimensional RuCl3

TL;DR

This study investigates point defects in monolayer alpha-RuCl3, revealing how different defects influence magnetic states and optical properties, aiding defect engineering for quantum spin liquid applications.

Contribution

First-principles simulations identify the most stable point defects in monolayer alpha-RuCl3 and analyze their effects on magnetic and optical properties.

Findings

Cl and oxygen defects favor zigzag-antiferromagnetic order

Ru vacancies favor ferromagnetic order

Optical spectra signatures can identify defect types

Abstract

Defects are crucial in determining a variety of material properties especially in low dimensions. In this work, we study point defects in monolayer alpha-phase Ruthenium (III) chloride (alpha-RuCl3), a promising candidate to realize quantum spin liquid with nearly degenerate magnetic states. Our first-principles simulations reveal that Cl vacancies, Ru vacancies, and oxygen substitutional defects are the most energetically stable point defects. Besides, these point defects break the magnetic degeneracy: Cl vacancies and oxygen substitutional defects energetically favor the zigzag-antiferromagnetic configuration while Ru vacancies favor the ferromagnetic configuration, shedding light on understanding the observed magnetic structures and further defect engineering of magnetism in monolayer {\alpha}-RuCl3. We further calculated their electronic structures and optical absorption spectra. The polarization symmetry of optical responses provides a convenient signature to identify the point defect types and long-range magnetic orders.