Abstract: Based on the density function theory, using the first-principles projector augmented wave potential under the generalized gradient approximation, we investigate the electronic structure and magnetism of zigzag silicon nanoribbons with a monovacancy or a divacancy.The results show that Zigzag silicon nanoribbons with a monovacancy (a divacancy) of different position will become a nine side ring (octagon ring) after structural relaxation, the same kind of defect is easier to form in edge region of Zigzag silicon nanoribbons.Either a monovacancy or a divacancy at the center of ribbon, Zigzag silicon nanoribbons change an antiferromagnetism semiconductor to an antiferromagnetism metallic.However, when a monovacancy or a divacancy deviate from the ribbon center, zigzag silicon nanoribbons become ferromagnetic metallic, the difference charge densities are localized only at one edge further to the vacancy, this brings potential applications in the field of spintronics for zigzag silicon nanoribbons.

Key words: Based on the density function theory, using the first-principles projector augmented wave potential under the generalized gradient approximation, we investigate the electronic structure and magnetism of zigzag silicon nanoribbons with a monovacancy or a divacancy.The results show that Zigzag silicon nanoribbons with a monovacancy (a divacancy) of different position will become a nine side ring (octagon ring) after structural relaxation, the same kind of defect is easier to form in edge region of Zigzag silicon nanoribbons.Either a monovacancy or a divacancy at the center of ribbon, Zigzag silicon nanoribbons change an antiferromagnetism semiconductor to an antiferromagnetism metallic.However, when a monovacancy or a divacancy deviate from the ribbon center, zigzag silicon nanoribbons become ferromagnetic metallic, the difference charge densities are localized only at one edge further to the vacancy, this brings potential applications in the field of spintronics for zigzag silicon nanoribbons.