Point defects in two-dimensional RuCl3

Abstract

Defects are crucial in determining a variety of material properties especially in low dimensions. In this work, we study point defects in monolayer \ensuremath{\alpha}-phase Ruthenium (III) chloride $(\ensuremath{\alpha}-\mathrm{Ru}{\mathrm{Cl}}_{3})$, 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 $\ensuremath{\alpha}-\mathrm{Ru}{\mathrm{Cl}}_{3}$. 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.